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I had planned to write my companion piece analyzing overlooked/underlooked prospects, but Steve Adler at Friarhood posed an interesting question on his website about left-handed slugging Padres at Petco. His article brings up some pertinent ideas as to whether the Padres have had a bona fide lefty slugger with a tendency to pull. Consequently, he wonders if Petco has been given an erroneous reputation as a lefty killer.

The question got me thinking, and I honestly couldn’t come up with any pull lefty sluggers except for Ryan Klesko, and he was at Petco near the end of his career. Adrian Gonzalez was a lefty slugger, but he did not rely on the ability to pull for much of his power.

So, when the lefties don’t come to you, you go to the lefties. I compiled a list of 15 left-handed hitters who have had 25 or more at bats at Petco. Why 25+ AB’s? Well, it’s not a great sample size, admittedly, but after doing the research, I wanted to include many players in the analysis. Now, they’re not all “sluggers,” in a true sense either, as the lowest career SLG% on my list belongs to Ichiro Suzuki at .421. I wanted to take a somewhat broader approach in looking at how lefties have hit for extra bases at Petco.

I researched the players’ career at bats at Petco, focusing on 2B, 3B, HR, and SLG%. I then compared their Petco SLG to their Career SLG. The results were interesting. For the table below, I sorted the data based on the amount of change between their SLG percentages.

PLYR AB 2B 3B HR PetcoSLG CareerSLG Change
J. Loney 26 1 0 0 0.154 0.432 -0.278
C. Gonzalez 82 4 0 2 0.354 0.521 -0.167
C. Utley 78 4 0 2 0.410 0.505 -0.095
P. Fielder 61 3 0 4 0.459 0.540 -0.081
A. Gonzalez 1410 66 5 57 0.442 0.514 -0.072
E. Hinske 30 3 0 0 0.400 0.437 -0.037
I. Suzuki 92 4 1 0 0.391 0.421 -0.030
A. Huff 93 6 0 3 0.441 0.466 -0.025
T. Helton 34 4 0 1 0.559 0.550 0.009
R. Howard 78 5 1 5 0.590 0.560 0.030
J. Heyward 36 4 0 1 0.500 0.427 0.073
A. Dunn 90 4 0 7 0.578 0.503 0.075
A. LaRoche 106 10 0 7 0.594 0.478 0.116
B. McCann 67 6 0 4 0.627 0.486 0.141
J. Votto 40 2 0 4 0.750 0.550 0.200

As you can see from the table above, of the 15 guys profiled,  eight have seen a decrease in their slugging percentage points while playing at Petco. For those eight players, the average decrease in SLG was seven points. For the remaining seven players, their SLG% increased at Petco. The average increase for that group was over nine percentage points.

So, what in the world does all of this mean?

I’m definitely not a sabermetrician, and my wife (as well as my English students) would certainly question my proficiency in mathematics, but it seems to me that it’s a coin toss as to whether a player’s ability to hit for extra bases is hampered by Petco. In James Loney’s case, his slugging drops a whopping 28 percentage points in San Diego…but then again, he barely qualifies with 26 AB’s. Carlos Gonzalez, on the other hand, has 82 AB’s but sees a point drop of 17 in his SLG percentage. On the opposite end you find that Joey Votto swings for extras nearly 20 points better.

I think, in order for the park to have a reputation as a place where lefties can’t hit, you’d like to see some more definitive results. Instead of eight…maybe that number should be more like 10 or even 12. Or…maybe their production should drop more dramatically. Instead of seven percentage points, maybe closer to 10? In this comparison, the data seems to point to Petco being fairly neutral to lefties and their ability to hit for extra bases.

Now…this is certainly no standard regression analysis. There aren’t any figures for variance or deviation. Are there flaws? Sure. Maybe the comparison between Petco SLG% and career SLG% isn’t comparing apples to apples. Maybe day games vs. night games or weather should be a factor. Maybe the pitchers they faced should be included in the analysis. Maybe I should have calculated their SLG% after pulling out the Petco AB’s. The list goes on and on.

But that’s the thing about studying baseball and statistics. There are always “ifs” and “maybes” when looking at the data. I guess the point of this piece, then, is to get the conversation going and discover some more angles on this topic. It is true, I’ve heard Petco described as a place lefties go to die, but I’m starting to question what information that reputation has been built upon.

I have seen lots of good work done on how Petco suppresses offense. And the data above bears this out as well. The average career SLG% for those 15 players is .493. The average Petco SLG% for that same group is .483, a fairly significant 10 point drop in slugging percentage points at Petco.

However, if we start specifying that a certain type of hitter is stifled, we should tread carefully before making that final determination.

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