In an article I wrote for my blog recently, I wondered why we neglect to dock Matt Cain "points" for pitching in AT&T Park, a pitcher-friendly ballpark, while at the same time being very mindful of Coors Field in evaluating the MVP award candidacy of Carlos Gonzalez. During the 2010 season, Gonzalez posted an OPS of 1162 home, but a more average-looking 775 OPS on the road. Similarly, Cain has a career 3.19 ERA at home but 3.76 on the road.

My point for writing this is not to criticize Cain for his home/road splits; I bring it up only to explain the inspiration for this research. Instead, I am interested in finding out how he has evaded his ERA retrodictors so consistently. Since becoming a regular in the Giants' starting rotation back in 2006, his SIERA has ranged from 3.90 to 4.23 but his ERA has ranged from 2.89 to 4.15 (his rookie season).

His home stadium, AT&T Park, which had a home run park factor of 82 for left-handed hitters in 2010, has helped him out quite a bit over the years (SIERA and other run estimators do not factor in park effects) but he has performed better than expected on the road as well. In discussing this issue with commenters on my blog and with the fine folks on Twitter, the consensus seems to be that he is a master at getting the weak fly ball.

From 2008-10, Cain has allowed the fifth-most fly balls (over 44 percent) among Major League starting pitchers. His HR/FB rate ranged from 6.8 to 8.4 percent. Even on the road, Cain has been stingy with the home run, as his career average HR/FB is only 7.4 percent and 6.7 percent at home. With nearly 6,400 total balls put in play, we certainly have a decent enough sample size to conclude that he has an ability to induce weaker contact. But is it necessarily true?

Cain's career BABIP is .270, 30 points lower than the .300 average for pitchers. Contrary to popular belief, the bulk of the difference does not come from fly balls. Cain's ground ball BABIP is 21 points lower, fly balls eight points, and line drives six points.

Can we credit the Giants' infield defense over the years for helping lower Cain's ERA? Park-adjusted defensive efficiency (PADE) tells the story. In 2010, the Giants led the National League, converting over two percent more ground balls than the league average, given AT&T Park. In '09, the Giants led all of the Majors with a PADE approaching 3.0. Aside from '08, the Giants have been at or near the top during Cain's career.



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No, Cain does not induce many ground balls, but when he has, they have been converted into outs at a rate much higher than normal (for example: in 2010 17.7 percent of Cain's plate appearances ended in a ground out–Zack Greinke, who had a G/F ratio nearly twice that of Cain, was at 19.3 percent). That means fewer runners are reaching base, fewer are advancing on one of his many fly balls, and more runners are being stranded.

In addition to the groundballs, from 2006-10, Cain threw the fourth-highest percentage of infield fly balls at 13 percent. Almost all of the pitchers at the top of the IFFB rate list have lower-than-normal BABIP. The top-ten range from .265 to .284. The particular pitch with which most pop-ups are generated is Cain's fastball. Since 2008, 134 pop-ups have come from the fastball; 17 by slider; 12 by change-up; and eight by curve ball. The fastball has accounted for over 78 percent of infield flies.

Furthermore, in an e-mail with our own Mike Fast, he pointed out to me that a majority of Cain's outfield fly balls are hit to the opposite field. Opposite field fly balls tend to be weaker and hit towards the deepest parts of the ballpark, which goes a long way towards suppressing home runs as well as hits in general.

I think we now have enough information to conclude that Cain's over-performance of his ERA retrodictors is legitimately assisted by three factors:

  • His spacious home ballpark
  • Significantly above-average infield defense, especially in the range department
  • A legitimate ability to induce weak pop ups and opposite-field outfield fly balls due to his fastball

So long as he continues to pitch in a spacious home ballpark, has a great infield defense behind him, and keeps his fastball at a consistently elite level, Cain should continue to defy expectations. Saberists will continue to underrate him (as I did prior to this research). Cain may be a lot of things, but he is not a fluke, despite what his ERA retrodictors say. There are exceptions to every rule, and Cain has proven himself to be one of those exceptions.

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As a Giants fan I find it hilarious you're trying to argue that the infield range is what's helping cain. outside of omar vizquel, no giant infielder in the past few years has had great range. all are very solid at catching the throwing, but uribe, renteria, sandoval, huff...none of these guys inspire "range." the other points are solid. but i think his ability to get the big k in pressure situations is more an indicator of why his ERA stays low than the infield range...
Per Baseball Reference, Matt Cain's K/PA:

- High Leverage: .183
- Medium Leverage: .203
- Low Leverage: .202

- With RISP: .198
- Runners on: .191
- Bases empty: .205

I don't think the evidence supports Cain getting more strikeouts in more important situations.
Looking at nFRAA range runs for the Giants infielders from 2006-2010, it's a mixed bag.

Feliz +54 runs
Vizquel +28
Ishikawa +20
Klesko +15
Huff +14
Uribe +8
Sanchez +5
Castillo -3
Frandsen -4
Renteria -5
Burriss -6
Sandoval -12
Aurilia -13
Durham -46

Durham is the only awful one, and both Feliz and Vizquel were quite good. Overall it's a somewhat above average group.
Another way to look at it is to simply look at the batting average on ground balls. Matt Cain's career batting average allowed on ground balls is .217. The Giants team from 2006-2010 was at .2336, and the National League was at .2374.

If we assume that Cain had an average set of Giants defenders behind him throughout that time (big assumption), then his fielders gave him slightly above average performance on ground balls, but his performance on ground balls was quite a bit better than an average set of his infield defenders would suggest.
I'm just happy you used the term "retrodictors".

(Yes, I'm a science/stat geek)
I personally love the term for it. Not quite predictors, but not quite ERA. Perfect term for it.
What data are you using to support the range of the Giant's infield? UZR? I certainly would'nt have described Renteria et al as particularly rangy. Not saying the conclusion is wrong, just that it isnt supported by data in the article and would seem to conflict with direct observation.
Perhaps singling it out the way I did was an error in judgment since it is not a critical factor in Cain's success; it's just one piece of the puzzle. The reaction seems to be that I'm saying it's a huge reason, but I did not intend to portray it that way.
Everyone focuses on HR/FB and flyball BABIP as the reasons for Cain's success. IMO, it was quite a nice observation that groundball BABIP is also a driver of his success.
Isnt it possible that Cain has a "skill" to pitch to his defense, which would influence the BABIP for GB as well as FB? How do you control/test for that in forming these conclusions.
Cain certainly could pitch to his defense, or even environmental factors. In 590.1 IP at home, he struck out 472 batters (7.2 K/9); in 505.1 IP on the road, he struck out 434 batters (7.7 K/9).

FanGraphs doesn't show any other incredible split gaps as far as I could tell (even for LD/GB/FB), but the home/road K/9 did stand out to me. He may pitch more to contact at home because it's friendly for fly ball pitchers.
How do you think Tejada's lack of fielding ability will impact Cain this year?
I don't think it'll be a huge deal. Cain induced ~250 grounders last year. If you figure that they're evenly split among the four infielders (they're not), that only amounts to about 63 apiece. If Tejada converts two percent fewer ground balls into outs than Sandoval (.947 fielding percentage last year to Sandoval's .962), then it's only one or two extra base runners for Cain.

Obviously, that was just a rudimentary illustration, but even if Tejada is much, much worse than his predecessors, it's not going to affect Cain that much.
It seems a bit disingenuous to compare Cain's home/road splits to CarGo's. This isn't the deadfall era, a 3.76 ERA is still far above league average. 
Deadball, damn autocorrect
I agree that it is a disingenuous comparison. I brought it up to illustrate how my prior notions about Cain were changed after doing a bit more research.
Cain certainly has the ability to induce weak contact on grounders, and to generate opposite field weak flies (especially from LHB's). The explanation, based on what my eyes tell me, is Cain's changeup. The pitch has exceptional late fade to his arm side, which is a rare and effective commodity, one that Tim Hudson has used for years with his split. I would be curious to see the results if you ran similar numbers for Huddy.

This is just anectdotal evidence, seen with mine own eyes, but I think it can be quantified via Pitch f/x (paging Mike Fast). The change is Cain's best pitch, thanks to its being virtually indistinguishable from the fastball. I described it a bit further in this article for BDD: