xWHIP 2.0: The Next Generation

The following article is from my most recent article for The Hardball Times.

A few months ago, I debuted the first version of the expected WHIP (xWHIP) calculator, which took a pitcher's batted ball distribution and, in determining an expected number of hits, calculated that pitcher's expected WHIP. The tool was tinkered with and refined until version 1.4.3 was released and that, until now, has been the primary xWHIP tool available. xWHIP 1.4.3 overexpected WHIP a bit, but was otherwise pretty solid. Especially for relative comparison purposes, xWHIP 1.4.3 was a useful fantasy tool.

Not long ago, I was introduced to a fellow stathead by the name of Martin Alex Hambrick. He had done some number tinkering similar to what I had done independently with the xWHIP calculator, and he had an idea. He brought that idea to my attention, and from it a new formula for expected xWHIP was born.

Alex's idea was that a pitcher's actual innings pitched (aIP) are as much the by product of luck as expected hits (xHits). The theory is that a medley of defense, umpires, errors, random luck and the like skew the length of innings. The pitcher, for example, does not particularly control dropped third strikes by his catcher.

This idea is somewhat captured in the K% (K/TBF) and BB% (BB/TBF) movement of sabermetrics that rejects K/9 and BB/9 because the length of innings is largely out of the control of the pitcher, thereby skewing both K/9 and BB/9. Accordingly, we began work on a new denominator for xWHIP that incorporated an expected innings (xIP) total based on a pitcher's outs-creating events.

With this idea in mind, we began work on a new xWHIP calculation. Law school delayed my work on a final formula until this week, but with "way too much time on my hands" (i.e., any lawyers out there need a law clerk for the summer?), I finally got around to hammering out a reliable formula and user-friendly interface, calibrated to Baseball Info Solutions (BIS) data.

The current formulation for expected innings is as follows:

xIP = ((K*1.000075)+((BB-IBB+HBP)*0.00016)+((0.808)*GB)+((0.278)*LD)+((0.992)*IFFB)+((0.745)*OFFB)+(0.020099*(BB+HBP+xH)))/3

The coefficients in the above formula represent the expected outs by event rate. You might notice the two percent adjustment applied to both modified walks (BB-IBB+HBP) and expected hits (xH). That figure represents a ten-year average outs-per-runners-put-on-base rate (ORB). ORB encapsulates the ten-year league average pickoff and caught stealing rates.

Because catcher defense and a pitcher's pickoff talents are difficult to measure, and also not widely available, using a league average rate helps make the calculator more accessible. The final xWHIP figure should be mentally modified based on one's own perception of a catcher's pickoff ability or a pitcher's pickoff ability. If Jason Varitek is the catcher, you might want to raise the pitcher's calculated xWHIP, while the opposite would be true for those pitchers handled by Yadier Molina.

Alex is working on a simplified "Quick xWHIP" formula that simplifies the xWHIP calculation even further, to the point that you could do it on a calculator. He'll tell you more about that (and the accuracies of both xWHIP 2.0 and Quick xWHIP) in a (near-) future post. All I can say for now regarding the calculator's accuracy, at least to some degree of certainty, is two things. First, xWHIP works best—that is to say, it is most predictive—when you use multi-year data rather than year N-1 data. Second, the R^2 of the data seems to be solid for a predictive state.

Someone once told me (or maybe I just read it somewhere) that an R^2 of .30-.35 is strong for a predictive stat, while a .60 or greater R^2 is what is required of an evaluative stat. Using 2007 xWHIP 2.0 to predict 2008 actual WHIP resulted in an R^2 of .34 amongst the 78 pitchers who faced a minimum of 500 batters, compared to an R^2 of .26 for 2007 actual WHIP. Likewise, using 2008 xWHIP to predict 2009 actual WHIP resulted in an R^2 of .36 amongst the 80 pitchers who faced a minimum of 500 batters, compared to an R^2 of .30 for 2008 actual WHIP.

Strangely, however, using 2009 xWHIP to predict 2010 xWHIP amongst the 82 pitchers who accrued 500+ total batters faced merely resulted in an R^2 of .15 (compared to a .14 R^2 for 2009 actual WHIP). Maybe I crunched the 2009-2010 data incorrectly. Maybe this is a sample size issue. Maybe not. As I mentioned above, Alex will supply more details on the accuracy of xWHIP 2.0 shortly.

I also tinkered some with the expected hits formula, but the changes are relatively minor and hardly warrant discussion. The important thing to note about the new xWHIP tool is that it is now calibrated per the past five years of BIS data rather than Game Day. I have done this because I believe that Fangraphs utilizes BIS, not Game Day, as their source for ball in play (BIP) data. Accordingly, this should make the tool more accurate for the average user. Most of the data stood relatively stable, but here are the new expected hits by batted ball types:

• Popups: .004
  
• Groundballs: 0.236
  
• Outfield Flyballs: 0.250
  
• Line Drives: 0.716

These data points include home runs, which is why the Outfield Flyball expected hits rate is so high. If you take home runs out of the equation and account for them separately (as the xWHIP calculator does), the expected hits rate, per BIS, for Outfield Flyballs and Line Drives falls to .158 and .714, respectively.

You can download the new xWHIP tool, version 2.0, by clicking here. The password to utilize the xWHIP tool is still "soto 18" and the batted ball data you will need to plug in can be found at Fangraphs.com.

Picture below is a screenshot of the xWHIP 2.0 tool, which was used in my Zack Greinke forecast article. For explanatory purposes, this screenshot has the 2010 numbers of Roy Halladay plugged in.


As the instructions on the tool indicate, the gray cells are for data you should manually input. The magenta park factor cell is also a manual data cell, though the number should be left at "1.00000" unless you have the relevant park factor HR/FB index figure. You should not enter any data into any of the blue, green or yellow-orange cells.

The green cells feature the line drive-regressed expected-ball-in-play data. The yellow-orange cells display the expected innings, expected hits and expected WHIP for the pitcher, irrespective of defense. If you enter data into the Team Innings Pitched and Team UZR gray cells, then the blue cells will display a crude defensive adjustment to the expected hits total, assuming uniform defense and that all saved hits would be of the singles variety. All of the data cells are pre-formatted to visually round all numbers to keep the sheet clean, though cells will retain the full value of any number entered.

I also included a cell for xWHIP 1.4.3, calibrated from Game Day to BIS, in case people wanted to know a player's expected WHIP using expected hits and actual innings, rather than expected innings.

I hope everyone enjoys this. If you have any questions/concerns/comments/criticisms, please post them in the comments below or email them to gameofinchesblog@gmail.com, with the subject line "xWHIP 2.0 Calculator."

On a final note, I would like to give a special thank you to several of my THT colleagues who have been invaluable in the creation of the xWHIP 2.0 tool. Without the assistance of Derek Carty, Dave Studemund, and Harry Pavlidis, none of this would have been possible. I apologize to each of you for my incessant e-mailing in attempt to work out the mathematical kinks in the formula.

Draft Tip #1

With fantasy baseball drafts still 2-3 months away, I am going to start cataloging various essential draft tips and tidbits I uncover while doing baseball research. This is tip #1.

Today's tip relates to poor-control starters and ERA. You like Morrow's upside? Let me warn you of his downside.

In doing some excel charting today, I discovered that the average ERA of a starting pitcher with a BB/9 greater than 4.00 over the past three seasons was a whopping 4.51. The league average ERA for starters was only 4.17 over this period, however.

Those high K, high BB guys like Bud Norris, Justin Masterson and Brandon Morrow seem nice, but you need to stay grounded and be cognizant of the risks inherent in their enticing peripherals. Of the 32 starters with BB/9 greater than 4.0 over the past three years (min. 150 IP), only Edinson Volquez, Rich Harden, Clayton Kershaw, C.J. Wilson*, Carlos Zambrano, and Yovanni Gallardo posted ERAs under 4.00. Don't forget poor control guys also mess with your WHIP.
*C.J. Wilson pitched exclusively in relief in both 2008 and 2009.

You've been warned.

Sexy Rexy's Drafting Strategy

So I have helped you (or like two people who may have actually read and liked my drafting tips) on some basic tips on how how to draft and maintain a good team. If you talked to me in past week or so, you know I have told you some ideas on my thoughts on players but I did not want to divulge too much information because there are some keys guys I wanted and did not want others to really know about them. So here we go,

1) I literally did research on every single projected starter. This allowed me to see which positions had the most depth. To me, 3B, 1B, SP, and OF had the most depth. I thought 2B and especially SS were awesome at the top and while I thought they had little depth but still some quality guys like Kelly Johnson, Rickie Weeks, Christain Guzman, and Ryan Theriot that were available in much later rounds. For me, if I didn't get J-Roll, HanRam, or Jose Reyes in the first round, there was no reason to draft a SS until like the 18th round, which allowed for great flexibility. Despite some quality 2B I could get around the 15th round or so, I still wanted a top tier 2B which I had to get in the top 3 rounds.

2) I took on the Sam Walker/Fantasyland approach of the trifecta pitching. This really isn't hard to do in non-auction leagues but I really wanted some stud pitching at the top of my "rotation". Yes, there is plenty of SP depth, but if I stocked my team with late round SP, my "rotation" would be nothing more than average. Because I was able to get a quality SS and quality OF later in the draft, I was able to get those positions I wanted later while getting above average to great SP in earlier rounds. A big problem I found is that a lot of top tier pitchers were young and abused/ in the WBC so seemingly more prone to injury, guys like: Tim Lincecum, Cole Hamels, Jake Peavy, and Roy Oswalt immediately came off my list. This left the top tier pool mainly consisting of Arizona pitchers. I ended up taking CC Sabathia as my first pick and although he's abused and I didn't like it a whole lot, I feel his past and his age make him a better candidate than most other pitchers.

3) My ideal players are guys with high BA (above .280), can go at least 15/15, and a high OPS. (To me, because R and RBI are not stats based on individual performance- they're based on the team and position in lineup- if a guy has power and can get on base a lot, they're more inclined to get R and RBI). Surprisingly, there were plenty of these guys which were: Ian Kinsler, Brandon Phillips, David Wright, Hanley Rameriz, Jose Reyes, Ryan Braun, Alfonso Soriano, Grady Sizemore, Carlos Beltran, Hunter Pence, Matt Holliday, Jayson Werth, Elijah Dukes, Nate McLouth, and Matt Kemp. Pretty elite group, no? The problem is that once the 3rd round starts, you'd be hard pressed to find any of these players. But two guys on this list stuck out to me: Jayson Werth and Elijah Dukes. These are two quality guys that go under the radar and thus I can get at lower rounds. So then, all I did was take a closer look between these players to determine which ones I wanted.

4) There still are certain positions that needed to be filled so I filled those positions with specialized players- mainly players with a lot of HR or SB, preferably with a BA and OPS if possible. I used these players to fill 1B, OF, 3B, and Util (mainly depending on my position in the draft, i.e. if I got Pujols or Wright I wouldn't need to fill 1B/3B respectively) The big name that jumped out to me was Jacoby Ellsbury- a guy who will probably by one the of the best OF in terms of SB with a high BA and a decently high OPS. For 1B, I needed pure power foremost then comes BA. Because I was just decent in HR everywhere else, I just targeted Carlos Pena. Although his BA pisses me off a bit, I think it's OK considering my high BA elsewhere and like I said, HR comes first. The 3B I targeted was Garrett Atkins. In my research, he came up as an Aramis Rameriz but with a .300+ B.A., which comes extremely useful to me. And because he was less values in the draft than other 3B like ARam, I could get a quality 3B a bit later in the draft.

5) So here was a list of specific players I WANTED: Kinsler, Ellsbury, Dukes, and Werth. I love Kinsler and I knew that I probably couldn't get him unless I had a late first round pick, and just my luck, I had the 9th overall pick. In the first three rounds I wanted a combination of 2B, SP, SS, and OF. (Now I clearly would have to change my strategy depending on on my draft position but...) I was able to get Kinsler in the first. Now I wanted Johan Santana in the 2nd and thus get the best available OF in the third, but Since Johan was taken I went with one of the best OF on the board that fit #2 (which was Soriano- admittedly though I took this pick in haste) and luckily CC came to me in the 3rd. Honestly, I thought CC would get taken so the next top tier SP would have been Brandon Webb (and maybe in some ways Webb would have been better) but I didn't want to reach and Sabathia was still available. Now base on previous drafting I knew Ellsbury generally went in the 4th and Atkins generally in the 5th so while they may have been slight stretches, I wanted those players. So in the first five rounds I got a 2B, Of, SP, OF, and 3B. I knew Werth generally went in the 12th so that's where I picked him up and Dukes and Guzman/Theriot (really the only SS I liked outside the first round) go really late so I was able to get some quality SP and RP, I think, between rounds 8-15.

7) I had back up plans just in case things went wrong. Joey Votto was a great 1B to pick up in case the 1B went higher than positions I wanted to take a 1B; Corey Hart was my substitute to Ellsbury; I could get a quality 2B like Brian Roberts, Dustin Pedroia, or Brandon Phillips in the 3rd round or Rickie Weeks and Kelly Johnson in much later rounds; I could have (and did) gotten a SS really late in the draft; 3B was deep so if someone overvalued Atkins I was willing to go after I guy like Edwin Encarnacion in much later rounds; Chris Young would have been an acceptable substitute for Werth; Jack Cust and Jim Thome are fine power/Util guys in later rounds... Anyway, despite my structured attempts in round 1-6, I had a back up just in case.

So now I have given up my secrets for this year's draft. The only draft that mattered was David "MVP" Eckstein's pay league and now that that's done, feel free to take my secrets. Plus, my strategy will change for the next drafts, I could care less really if I lose others leagues, and I still have some players up my sleeve. Enjoy picking at my brain!

Sexy Rexy’s Drafting Tips

With Opening Day seemingly right around the corner, I'm sure you all are in the midst of drafting for your fantasy baseball team. Wait, what am I saying, I know all five people who read this blog and you all are in my fantasy league. So because I know you will be drafting soon, I'm here to help you out.

Although I would like to say, I've never played roto before this year and the three years prior I haven't done THAT well so maybe I don't have the best ethos (read more Aristotle dude), but I'm confident these tips will help. Also, I did win my fantasy football league a couple months ago so maybe I'm on the up and up? Haha

Pre-Draft:

1. You can never do enough research. For any fantasy sports, you are essentially predicting the future. MVP Eckstein has done a great job in his analysis of John Danks and Edison Volquez and how they might fare in 2009. Unfortunately, that analysis is long and tedious. I personally have signed up for baseball prospectus for offensive players and have my own system using certain past stats for all pitchers. MVP Eckstein also posted a bit back about some free websites to help you out. Me personally, I have analysis of every single projected starter (both offense and defense). The point is I recommend you find a way to get analysis on every single player and then some. This may seem excessive, but you can never do enough research
2. Know what stats your league has. I'm in four league and all have different stats they use to judge players. Not all leagues use the basic 5x5 format. In another random football league I was in last year, I didn't realize that essentially one great to above average QB could win head-to-head match ups for you by himself every week. This fucked me because in my normal Fantasy Football strategy is to draft a QB late so I got sort of a shitty QB. Clearly I did not win that league.
3. Ready, aim, TARGET! Make sure you have multiple players you are targeting, for both big guys AND sleepers.
4. Strategery. Have a specific strategy in mind. Take Fantasyland for example. Author Sam Walker had a pitching strategy mind; he was going to take two stud SP and one stud RP and hoped to build enough of a pitching lead to then trade away from P for offense. Have something like this in mind.
5. Don't worry about big names. Trust whatever research you do.
6. Practice, practice, practice! There are many great sites like MockDraftCentral or ESPN that you can go to hone your skills

During Draft:

7. Play the expectations game. The key to drafting is all relative to how other people view the players you want. Don't trust that counter thing on the side of yahoo or ESPN or whatever. For example, I drafted a player probably WAY too high, but I don't really care. I got most of the players I wanted later in the draft PLUS this one player. People may have laughed at me then but we'll see who's laughing when we actually play. If you've done all the above well, don't worry about what other people think of your picks
8. Adjust. For by now you've come up with a pretty solid draft strategy. That will change because there will always be people who don't know what they're doing or people who will take a player who want and you'll be like, "WTF! Why would you ever take THAT player so high!?" It'll happen and you need to prepare for it. So despite all your preparation, practice, and targeting, just be aware that things won't go as planned.
9. Learn from your mistakes. I myself have of course made a few and that hopefully will help me for this year
10. Don't be hatin! Don't draft a player just to spite someone else. I.E.- last year in the second to last round I took Pat Neshek to spite MVP Eckstein instead of this reliever I had on my team last year who I recently found out was going to be a closer, George Sherill. Sherill was picked up in free agency the next day. Sherill racked up SV and Ks and was a quality undrafted free agent closer. Neshek was out most of the year. The joke was on me.
11. Take risks in the very last rounds. Once you reach towards the end of the draft, the players that you can choose from are pretty slim. Unless there is a player you are targeting or think should have been drafted higher or something along those lines, draft risks. Chances are, no matter what, your last round picks won't be on your team anyway.

Post Draft:

12. Be on the lookout for breakout players. I'm sure not many people in your league last year drafted people like Edison Volquez, Carlos Quentin, or Nate McLouth. Do your best to get them early but look at peripherals to make sure you're not just getting a player who's having a good couple weeks and then will suck again (I don't know what peripherals actually are but there's a way to look at them)
13. Patience is a virtue. I myself am I huge hypocrite of this because I am an impatient motherfucker and I'm positive this will hurt me when I play roto this year but it's something I, and you, should do.
14. Don't be complacent. Be on the lookout to help your team but don't make any trades or pick up any guys just for the sake of it.

This is all the tips I'm going to give away right now. I'll tell you guys my strategy after our drafts. Happy drafting!