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Saturday, August 20, 2011
Jair Jurrjens' date with regression

By Kevin Orris

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).

Perhaps the most intriguing part of his success was his decline in velocity. According to Baseball Info Solutions, his fastball velocity has dropped each year since he debuted in 2007; however, his biggest decline has taken place over the last year. In 2010, Jurrjens featured his fastball 63.9 percent of the time, averaging 91.1 mph while dropping his usage to 57.6 percent this year, averaging 89.2 mph. It’s quite possible that the decline in velocity is intentional on his part, in order to establish better control. Whether it was or wasn’t by design, he’s delivering a career-best walk rate of 2.4 BB/9, which ranks 36th among qualifying starters.

As David Brown found in 2009 at Baseball Time in Arlington, there is a very noticeable correlation between a pitcher’s fastball velocity and his ERA, further proving that Jurrjens was defying the numbers through the first half of 2011.

From a non-sabermetric perspective, there have been other noticeable changes in Jurrjens’ game. On April 21, Jurrjens featured a new sinker grip that he learned from southpaw reliever Jonny Venters that drew rave reviews after scouts noticed his fastball began to flatten out in 2010.

"Just because he was pitching like a [No. 1] doesn’t make him a [No. 1]," said one baseball executive. "If he still pitched in the AL, he would strike out even fewer batters."

Although Jurrjens received plenty of positive hype in the first half, it appears that people may continue talking about him -- but for the wrong reasons.

Kevin Orris is all-knowing and wise writing for Capitol Avenue Club, and tweets at @kevinorris.