Jair Jurrjens’ Date With Regression

From SABR member Kevin Orris at ESPN.com on August 20:

Entering 2011, most analysts didn’t spend much time talking about Atlanta Braves starter Jair Jurrjens. He was viewed as an average contact-oriented pitcher after posting a 4.64 ERA with just a 6.6 K/9 in 2010. To the surprise of many Jurrjens made the All-Star team for the first time this past July, but since that point, his ERA has risen from 1.87 to 2.84, an increase of nearly an entire run.

Sabermetricians were generally in agreement that regression to the mean was expected, and their expectations have certainly come through. Through the first half of the season, opposing hitters were struggling against him, hitting just .229/.276/.310 with a .260 BABIP but the results have since gone sour. Since the All-Star break, opponents have hit a whopping .295/.367/.571 with an increased .310 BABIP.

Looking back even further, Jurrjens was unlucky in 2010, posting a -0.45 difference between his FIP and ERA. This season, his FIP is 0.84 higher than his ERA, good for fifth among National League pitchers behind Johnny Cueto (1.56), Jeff Karstens (1.25), Ryan Vogelsong (1.06) and Randy Wolf(0.92).

Even with his recent struggles factored in, further regression is likely to occur. While Turner Field is considered a pitchers park, his ratio of homers to fly balls of 6.9 percent is much better than the league average (typically around 11 percent), along with his 79.8 LOB percentage (typically around 72 percent).

Read the full article here: http://espn.go.com/blog/sweetspot/post/_/id/15181/jair-jurrjens-date-with-regression

Originally published: August 25, 2011. Last Updated: August 25, 2011.