Petco Park is finally going be altered. Total balance between offense and pitching is not the goal of this effort. Petco will always be tilted in a pitcher's favor due to the lack of elevation and the cold, moist air of the bay off its concourse. The goal of initiating a construction project on the field in San Diego is to balance offense overall, and to balance offensive output between right handed and left handed batters. A nice side effect of any such maneuver is that Petco will no longer be such an extreme environment. Let's take a look at the new dimensions and how they would have effected last year's offensive numbers.
With the modifications, the fence in right field will extend from what was the middle notch of the short porch and run all the way to the alley in right center. This takes rightfield in by 11 feet at the end of the porch, 14 feet in straightaway right, and 20 feet in the alley. Not to mention the fence will no longer be the ridiculous behemoth it once was. The out of town scoreboard will be relocated, though it's future home has not yet been revealed. A seemingly more visually subtle change in left center will actually impact offense almost as much as the changes in right. You can see that fence will be bumped forward by 12 feet in the gap. The visitors bullpen will be moved behind the Padres bullpen, behind the wall, to the left of center. This removes a long lamented hazard from the field of play.
To study the possible effect of the new dimensions of the park, we need to look at batted ball data in the form of spray charts. I wanted to find spray charts that would allow me to see what the result of each Hit on the plot was (single, double, triple, homer), but I could not find a source this detailed. Because of this lack of data, I had to estimate that deep plot points for a Hit, must have been doubles. I took outs that landed beyond the new boundary of the field and added four total bases for a home run, and for each Hit beyond the new boundary, I added two total bases (to account for the change from a double to a homer). I have no way of knowing if the spray charts (from foxsports.com) are totally reliable, and therefore relied on guesswork, to an extent. Because of this, the following data is scientific in only the most casual definition of the word, but can provide us with a idea of how Petco may play in 2013.
We see that Chase Headley (a switch hitter) would have ended up benefitting the most from the 2013 layout, with Will Venable and Yonder Alonso (both lefties) tied with Carlos Quentin in second. John Baker and Alexi Amarista (also lefties) fall in the 5 and 6 spots. It is notable that the two top power hitters on the team (Quentin and Headley) would gain the most in terms of total bases. It is also notable that Will Venable gains a disproportionately high number of homers and total bases compared to his season totals. This makes sense, due to the fact that he is a dead-pull lefty. But let's try to figure out what a whole season at the new Petco looks like. To do this we need the rate at which total bases and home runs are being increased per plate appearance (the change in TB/HR divided by the total home PA of the players sampled, including those players who experienced no change.) Then we need to multiply that rate by the number of total home PA the Padres had last season to find the adjusted TB and HR totals. We can then compare the adjusted totals with others from around the league. We can do the same with the opposing teams.
The Padres had bad pitching last season, due to a high attrition rate in the rotation. So it should come as no surprise they would have given up the second most home runs of any staff, in a more balanced park. In 2012 they allowed the 17th most longballs in the Majors. At the plate, the Padres would have moved into the middle third of offenses, as opposed to the finishing in the bottom five in each category.
The New Era
The changes to the playing field at Petco look rather subtle, but the impact on offense could be quite substantial. However, more important than increasing offensive production in the immediate term, the Padres are counting on the alterations to help the club shape it's future. They have a surplus of talented prospects in the farm system and a new ownership group upstairs that wants to lure hitters (not just pitchers) to San Diego. By neutralizing what was an extreme environment they are completing a fresh start, renewing the faith.
*Infographics by RA Rowe