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Thursday, July 26, 2007
Should high HR pitchers pitch in low HR parks?
Buster Olney wrote this the other day (on ESPN.com):
“Livan Hernandez,” said a talent evaluator Saturday evening. “I’m surprised that nobody’s talking about him, because he’s out there [on the trade market].”
O.K., let’s fortget about the fact that this “talent evaluator” should probably be evaluating HIS talent as an evaluator, and that no one is talking about Livan because Livan sucks at this point in his career.
“The light bulb goes on: great postseason experience, minimal financial obligation (he’s making $7 million this season, and his contract runs out at the end of this year), a guy who has always taken the ball (nine straight seasons of 30 or more starts, and he’s got 20 starts so far this year). He is not an ace, he gives up a lot of hits, but he will generally keep a good offensive team in games.”
Let’s also forget about Olney writing that “he will generally keep a good offensive team in games.” (Isn’t that true about any bad pitcher?)
“The D-backs are fading, have the minor league arms to take his spot in the rotation for the last two months—and Livan is not really a good fit for them now, anyway, because he is not a shut-down kind of pitcher and they are struggling to score runs. The cost of trading for Hernandez would presumably not be that high.”
More garbage from Olney. Fading? Last time I looked, they were 1.5 games out of first! Struggling to score runs and he is not a shut-down pitcher? I don’t have to tell anyone on this blog that a good pitcher is good for any team and a bad pitcher is bad for any team, regardless of their ofense, although I suspect that there are minor differences in the value (above or below replacement) of a pitcher depending upon his team’s offense.
“He makes a lot of sense for a team like Atlanta, or a team like the Mets (where he could team with his brother, Orlando), or maybe the Phillies, although he would give up a lot of homers in their park.”
More garbage, but what I want to talk about is the last part of this sentence. Do pitchers who give up a lot of home runs do worse in a home run park (than other pitchers or as compared to a neutral or low HR park)?
I think it is conventional wisdom that if your team’s home park is a “HR park” like Philly was (they moved the fences out a little this year) and several other parks are and have been, that you should not acquire a pitcher who gives up a lot of HR’s. I also think that most analysts would agree with this. I am not sure that I have ever seen any research on this point, and if I am overlooking someone’s work, I apologize. This is a blog and not a venue for publishing formal research.
For batters, we (many analysts) don’t think that this is necessarily the case. What I mean is that we don’t think that a high HR batter will do particularly well in a high HR park or particularly poor in a low HR park (and vicer versa for low HR batters). The reason is that for batters who hit lots of HR, it is because they tend to hit the ball far when they hit a fly ball but don’t necessarily hit a lot more fly balls than a low HR batter. For pitchers, high HR pitchers tend to give up lots of fly balls and low HR pitchers don’t. The average distance of each group’s fly balls are not all that different.
Imagine a park whose fences were 450 feet all the way around. Only the “big hitters” (the ones who hit a lot of HR’s) would hit home runs. No one else would. Therefore you would want a big hitter in that kind of park, assuming everything else were the same. Now imagine a park where the fences were only 200 feet around. Who would you want hitting in that park? Just about any hitter who hits a lot of fly balls. Not necessarily the big hitters.
Anyway, let’s get back to the pitchers. Oh, and BTW, Livan Hernandez is NOT much of a high HR pitcher, despite the fact that he may have let up a lot of HR so far this year. Further proof that Olney is a dumpkoff, with all due respect, as I hear that he is a nice man. The presumption because of the dynamics of low and high HR pitchers is that a high HR park is not good for high HR pitchers because they allow lots of fly balls which turn into HR’s in parks that have high HR park factors. IOW, the presumption is that HR park factors tend to be multiplicative for pitcher HR rates (a linear relationship), whereas for batters that is not the case, again, because of the dynamics of what makes for a high or low HR batter, as opposed to pitcher.
First, I took all low and high HR pitchers in terms of their park neutral projection going into 2004, 2005, and 2006. The projections were based on their last 4 years HR rates (regressed and age adjusted), so that an 06 projection was based on data from 02-05, etc. I used only pitchers who had at least 400 IP in the last 4 years, so they were mainly starters. I took around the top and bottom 25 pitchers (with the 400 IP minimum) for each projection year, for a total of around 75 high HR pitchers and 75 low HR pitchers.
The HR rate for the low HR pitchers was 79% of average and for the high HR pitchers, it was 132% of average. Remember that these are projections and not actual historical HR rates.
I then looked at each group’s HR rate in the year of the projection (04-06) as well as their normalized ERC (NERC), where the average pitcher is defined as 4.00. Obviously the low HR pitchers were much better pitchers than the high HR pitchers and they got a lot more IP in the year of the projection than did the high HR pitchers.
I then looked at each group’s performance in high HR parks and low HR parks only. I used my own park factors to determine which parks were high HR and which were low HR. I just picked a few with the highest HR PF and a few with the lowest HR PF.
UPDATE!
I addes some years to the pitcher data and did a similar study with batters for 04-06 only. The results are in posts 19, 36, and 37.