July 26, 2005
Can Of Corn
Putting the Park Back in Park Factors
The (excruciatingly obvious) recognition that environment affects the game on the field has made impressive inroads in recent years. It's not uncommon these days to hear rank-and-file fans or mainstream analysts paying qualitative heed to this notion, which is a good thing. In seamhead circles, most commonly this discussion takes the form of park effects, which, as you know, entails making statistical calibrations to reflect the tendencies of a particular ballpark. After all, a run scored in Dodger Stadium in 1968 isn't the same as one scored in the Baker Bowl in 1932 or Coors Field circa 1998.
Speaking of Coors Field, thanks to its incontrovertible effects, you'd be strained to find any writer or team exec not at least dimly aware of how playing environment influences the game. For too long however, we've been reliant upon the broad brushstrokes of runs-based park factors; i.e., evaluating a park by its gross effects on runs scored while being heedless of its effects on component-level statistics like AVG, OBP and SLG. For instance, Dodger Stadium, generally speaking, suppresses run scoring not by cutting down on homers, but rather by cutting down on almost every other positive offensive event. Recognizing this conveys much more "actionable" knowledge than lamely offering, "It's difficult to score runs at Chavez Ravine."
Beyond even component-level factors is the notion that batters will fare differently in a certain park based on their handedness. For instance, Comerica cuts down on home run rates overall, but it does so by narrowly hindering left-handed power hitters and altogether crippling those hitting starboard. It's also worth pointing out that looking at single-year park factors is, I think, improper. At least a three-year factor should be used if you're interested in drawing any meaningful conclusions. All of this is to say the old method of looking at a single season's worth of runs-based park factors is wholly inadequate. You need multiple years' worth of data, and you need not only component-level factors, but also component-level factors broken down into left-handed and right-handed splits.
This raises the subject of platooning. For too long, platoon decisions have been informed by the handedness of the pitcher and the handedness of the hitter. Those are certainly eminently sensible considerations, but, in light of what we know about the indigenous tendencies of certain types of players, ending the platoon discussion at that point is darn well uninspired. Groundball and flyball tendencies of batter and pitcher should be considered, as should the micro-level dispositions of the park in question. This latter point can be particularly informative insofar as it applies to home runs, which, in my opinion, best combines variance and sample size among component stats. By that I mean, unlike, say, triples, you have enough home runs hit in each park to draw quasi-firm conclusions, and there's also enough variation from park to park that teams can use the information to gain an advantage. So should teams be wielding "park platoons"? Yes, in certain circumstances. Using 2002-2004 park data, observe how the following parks affect the HR rates of left-handed and right-handed batters:
Park LHB HR Factor RHB HR Factor Astros 84 116 A's 97 114 Cubs 97 137 Devil Rays 98 75 Mariners 113 86 Mets 115 77 Red Sox 76 105 Rockies 147 127 Tigers 93 74 White Sox 121 137
Included in the above table is any park with at least a 15-percentage-point difference in the HR factors for the left-handed and right-handed batters. This, of course, isn't groundbreaking knowledge. For instance, we've known and discussed for decades how Fenway is far more accommodating to right-handed batters than it is to their lefty-swinging counterparts. However, this knowledge doesn't seem to be utilized often enough in terms of lineup selection.
In particular, when toiling in one of the outlying stadiums traditional platoons might be wisely damned in favor of "playing the park." You'd probably do well to lard the lineup with right-handed batters when visiting Wrigley, Minute Maid or Fenway. A road set in Tampa, Detroit, Seattle or Queens should prompt you to play any remotely worthy left-handed bat. And so on and so on. Conversely, gerrymandering the rotation according to the schedule might be wise in order to avoid pitching lefties in certain parks and right-handers in certain parks. Needless to say, if you're one a denizen of one of these parks, these considerations become all the more vital. Given the extreme nature of their park splits, should the Cubs, Red Sox and Mets give thought to home rotations, road rotations, home lineups and road lineups? Perhaps so. At the very least, it's something to consider in a series of critical mass.
You'll notice that many of the parks above are in the same division. In this, the era of the unbalanced schedule, intra-divisional opponents can play a hefty percentage of their schedule in these parks. The Indians, for instance, by season's end will have played 35 games in these parks, which comes to more than 20 percent of their season. Is there ever a reason for them to, say, start Ron Belliard in Detroit or Ben Broussard in Fenway? Even accounting for favorable platoon match-ups against the pitcher in question, the environment can work so squarely against a player that the park's tendencies should hold sway. If teams are going to start leveraging park splits properly, having a strong bench and versatile pitching staff will become all the more important. On a wider level, if your team's home park is one of the extreme split variety, then that should inform the club's player-acquisition decisions. The Cubs, for instance, should think long and hard before signing an otherwise solid lefty starter who's prone to homers. Likewise, if the Tigers' lineup skews heavily right-handed, they're going to have trouble scoring runs at home.
It's often parroted that a manager's primary job is to put his players in a position to succeed. That entails more than favoring hot hands and thinking of platoons only in terms of batter-pitcher encounters. They're also a case of "man vs. environment." It's my impression that most organizations are neglecting this fact.