Thursday, May 21, 2009

A Look At Home Runs In Minute Maid Park

With the UW Club Baseball team, I had the fortune to play at a myriad of parks this last year. Many of them were, to say the least, not good. Aside from the poor infields and bumpy outfields that can be expected playing at public parks, one of the things that a player must adjust to is the distance of the fence. At one park I played at, the fence was concave - the shortest point in right field came about 30 feet to the left of the RF foul pole. In high school, a non-conference rival's field had the right field foul pole 240 feet from home plate.

Certainly, ballparks in the major leagues don't have dimensions that ridiculous. Still, some parks play very differently from others. One of these is Minute Maid Park. Famous for the Crawford Boxes down the left field line and the hill in center field, Minute Maid Park's dimensions make it a difficult place for opposing outfielders (and home outfielders, for that matter). Not only do the dimensions change how outfielders play, they also has drastic effects on the number of home runs hit .

The two points of interest mentioned above are what I decided to take a closer look at. Thanks to one of my favorite websites, , people can see the trajectory and distance of every home run hit in the major leagues. Here is a plot of all 43 home runs hit at Minute Maid Park entering last night's game.

The blue dots in the picture are the landing points of the home runs.

First, let's examine the home runs hit to left field. At first glance, it looks like these are all cheapies. This plot, however, shows landing points, and because of the wall behind the Crawford Boxes roughly 350 feet away from the plate, none of these HRs will look like they went farther despite hitting high enough off the wall that they would've traveled much farther. There have been 18 HRs hit to into the Crawford Boxes so far this year. Here they are in chart form.

There are only 3 HRs here over 400 feet. Not a whole lot of bombs hit here. However, the most interesting thing to note here is the number of parks that a ball hit with that trajectory would be a home run in. 11 of the 18 HRs would be out in every park. This isn't surprising, as the portion of the field we're examining is relatively close to the left field line, and a 370 foot homer down the line is out in any stadium. What stands out in this list are the 4 home runs at the top. Between these 4 home runs, they would produce a total of 10 HRs out of 120 possible. That's 8.3%. Let's take a look at these 4 home runs in a relatively neutral stadium - Atlanta's Turner Field.

Not only are those not HRs. Those aren't even close. Over 20 games, Minute Maid Park has added 4 HRs that wouldn't be a HR in the average ML stadium (or nearly any stadium, for that matter). Considering these balls are so far from the fence, it's probably safe to assume that an average ML left fielder could turn these balls into outs. That means that LF in Minute Maid Park adds 16 HR over a full season. According to linear weights, that's roughly 31 runs over 81 games.

Of course, not all of Minute Maid Park is built so short. Center field in Houston is the deepest in the majors at 436 feet, and that's even before taking the hill into account. Much unlike left field, center field tends to swallow up HRs and turn them into either doubles, triples, or outs. Here is a plot of Minute Maid park with 4 homers that are out in 27 out of 30 parks, but would stay in at the Juice Box.

In this picture, no home runs were hit between the two black lines coming out from home plate. The red dots show the HRs trajectory, the blue dots show the landing spot, and the green dots show their "Std. Distance", or their projected landing spot had they not hit elevated ground. Here are the 4 home runs in tabular form.

All of these home runs were farther than 414 feet in Std. Distance. These are the kind of hits that get deemed moonshots by the announcers. These are just examples. Across the league, there have been 198 home runs hit between the black lines in the above picture, and none of them have occurred at Minute Maid Park. That's 16% of the total number of home runs hit in the major leagues (1232 total), and yet, we see 0 of them in Minute Maid. If we take out the 4 home runs that were added by the Crawford Boxes, Minute Maid would've allowed 39 home runs as of yesterday's games. However, if we would expect 16% of the home runs to come from between the black lines, then that would mean that there are 6 would-be home runs missing. It seems, then, that at least so far this year, these two parts of Minute Maid combined have actually suppressed 2 homers over 20 games.

Over the small sample size, it is likely that the home runs added by the Crawford Boxes and those suppressed by the deep center field will even out. Minute Maid is also getting slightly more home runs than average in right field and left-center, to put it's 2.15 HR/G rate slightly above the league average of 2.08, consistent with its park factors over the years. Minute Maid Park is one of those quirky parks that, as a road team, certainly make you change the way you play both as an outfielder, a hitter, and a pitcher.

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