Petco Park's New Fences Made A Real Difference

I know that many of you watched a lot of Padres home games, many of you attended a lot of games at Petco Park and many of you gobble up every bit of information that comes out about the Padres and most of you already know or have ideas about the impact the fence move made in 2013. However, I ran across some data from the Fangraphs' Guts! pages that I wanted to share about how the fences affected play in 2013. On this linked page, you get all the data about Padres park factors.

The first column you see on the left is the Basic Park Factor. That's just run scoring. You can see there that in 2013 at Petco Park (referred to as 2013 Padres in the table) had a Basic Park Factor of 95, which was the third lowest in the league. However, you can also see that this represents an increase in run scoring. Petco Park had previously averaged a Basic Park Factor of 92. So, the park used to decrease run scoring by 8% and last year decreased it by only 5%. For an average run scoring team, that would mean that a Basic Park Factor increase of 3% would equate to about 10 more runs per season (81 home games).

For those that dig the long ball, the column you want to look at is obviously Home Runs. The Petco Park 2013 Home Run Park Factor was 98, just 2% below league average and 14th lowest in the majors. The average Home Run Park Factor for Petco Park prior to that was 89.8. That's an over 10% suppression of home runs when compared to league average and easily the stingiest park when it came to home runs. That is a pretty big leap. An average home run hitting team would hit somewhere around 6 more home runs over a season (81 games) at a park whose Home Run Park Factor increased by 8%. Here's the table for those that don't like clicking links:

In terms of raw numbers, the Padres released details at the end of October to MLB.com about some of the raw numbers they tracked during the season. They claimed that 21 "new fence" home runs were hit at Petco Park (that includes both the Padres and their guests). The HR numbers increased from 1.3 HR/game in 2012 to 1.8 HR/game in 2013.

Those raw numbers are just the 2013 season results. The park factors are actually 5 year regressions, so they are a bit more conservative when it comes to changes in stadiums. There's the possibility that the changes were a bit more dramatic in 2013 and will level off or that they are the tip of the iceberg. Time will tell as the small sample sizes become big ones.

Getting back to those Park Factors from Fangraphs, another interesting one comes to light when you look at handedness. They allow you to get a Park Factor split for the handedness of the batter. The one I found interesting was LH HRs. Fangraphs even mentioned this at the end of their article about Will Venable's new contract. The Park Factor for 2010-2012 for LH HRs had dipped all the way down to an 81. 19% below league average and easily the worst stadium for lefties to hit dingers. In 2013 it was 109. That's 9% ABOVE average and the 7th friendliest park for sinister four baggers in the major leagues. Looking at the other statistics' Park Factors, it would seem that everything LH increased in 2013 and everything RH stayed the same. Here's the table for Handedness Park Factors for the Petco Park era: