In the era of multi-purpose stadiums in the 1970s and 1980s, it seems that there were more similarities across the spectrum of ballparks than there is today. In the post-new Comiskey era, which began with Camden Yards, we’ve brought quirkiness back to the ballpark. We may not have returned all the way back to Ebbets Field, the Polo Grounds or the Baker Bowl, but today’s ballparks certainly don’t look alike. There are enough extreme characteristics in some of today’s parks to have a profound impact on players’ stats and careers.

The impact of parks on pitchers shows up several ways, but the most vivid is in the HRs a pitcher yields. Let’s look at two pitchers who have changed ballparks over the careers—moves which were beneficial to one and detrimental to the other. Aaron Harang began his big league career with Oakland, but then moved to Cincinnati, before he moved back to the west coast with San Diego and now the Dodgers. For right-handed (RHH) and left-handed hitters (LHH), the HR park factor for Cincinnati is 143 and 121, respectively (from Bill James Handbook—the average of the most recent 3 years). The index for Dodger Stadium is slightly above 100, while the other two ballparks Harang called home are well below 100, indicating they are pitcher-friendly, run (and HR) suppressing ballparks. Harang’s HR-rate as a Cincinnati Reds pitcher is 11.1% per flyball. His rate with the other 3 teams—all based in pitchers’ parks—is 7.5%. He clearly benefited by the move to San Diego and then LA. On the flip side we have Mat Latos, who has played for San Diego and Cincinnati. In San Diego, Latos notched a 7.9% HR/FB rate, while it soared to 11.8% in his first year as a Red. He mitigated the problem somewhat by being slightly less of a flyball pitcher in Cincy, but the leap in HRs is still a drag on his effectiveness.

There are four pitchers who standout to me as being mismatched with their home ballpark. Phil Hughes (NYY), Colby Lewis (TEX), Brian Matusz (BAL), and Rick Porcello (DET). Porcello has the reverse problem—and in a sense, it’s a smaller issue. He is an extreme groundball pitcher (approximately 90^th percentile for 2012), but he pitches in a massive pitcher’s park, where flyballs will do far less damage than in a hitters park. So, what’s the problem, since the Tigers still benefit from his high groundball rate? First of all, not with that defense they don’t, but that’s another issue entirely. My point is that Porcello should have greater value pitching elsewhere, with a team that has a ballpark that penalizes flyballs, rather than a ballpark that is forgiving, like Comerica. Flyball pitchers like Colby Lewis and Brian Matusz would be far more effective in Oakland, Seattle, or any of the west coast parks, which tend to be more cavernous and/or where the ball will not carry as far.

Phil Hughes is a fascinating case study. I’ve always believed that Yankee Stadium was one of the worst venues for him to pitch. A right-handed flyball pitcher, pitching in a park that has a LHH HR index of 153—second only to Coors Field. The reason I list the LHH HR factor is because he will face more than 50% LHH. (Incidentally, Yankee Stadium has a RHH HR index of 102.) If you take a close look at peripheral stats such as K-rate, BB-rate, etc., you will see that Phil Hughes and Jered Weaver are very similar. There are two huge differences between the two. Weaver has perfected a change-up, which he uses extensively to LHH, keeping the ball away from them. The second difference is the ballpark. Weaver pitches perfectly to his ballpark, yielding flyball after flyball, many of which would be HRs in Yankee Stadium, which turn into outs in Anaheim. If Jered Weaver were to pitch regularly in Yankee Stadium, he would either need to alter his gameplan, or be relegated to a middle/back-of-the-rotation starter. If Phil Hughes were to pitch in San Diego, Seattle, or another of the west coast pitcher-friendly parks, he would likely be a bona fide number two starter and frequent All Star. Yes, the ballpark can make a big difference.