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SIERA’s Luckiest Starting Pitchers

Posted By Mike Podhorzer On September 17, 2012 @ 8:15 am In Starting Pitchers,Stock Watch | 12 Comments

As we head into the final weeks of the season, it’s nearly time to get a jump on next year’s research. One of the first exercises worth performing is comparing a pitcher’s actual ERA with his SIERA. While in some cases there are legitimate explanations for over or underperformance of SIERA marks, for the most part, you should treat SIERA as your baseline for your next season ERA projection, rather than actual ERA. Here are the five pitchers who have outperformed their SIERA marks the most this season.

Name K/9 BB/9 ERA SIERA Diff
Jeremy Hellickson 5.9 3.1 3.22 4.59 -1.37
Kyle Lohse 5.8 1.6 2.81 4.15 -1.34
Jered Weaver 7.0 2.1 2.74 3.90 -1.16
Ross Detwiler 5.6 2.6 3.16 4.25 -1.09
Aaron Harang 6.8 4.2 3.79 4.79 -1.00

Jeremy Hellickson

Surprise, surprise, Hellickson appears at the top of this list for the second consecutive year. Seriously, has that ever been done before? Last year, there was some decent ammo for Hellickson supporters to use to justify his dramatic outperformance of his SIERA. You had an extreme fly ball tendency and a sky high IFFB%, both of which helped to deflate his BABIP, combined with excellent defensive support, as the Rays easily led baseball in UZR/150. This year, however, there is a whole lot less that might explain his magic. He’s allowing line drives at just an average clip, his pop-up rate has declined significantly and now sits barely above the league average, and he’s inducing fewer fly balls, all of which normally raise BABIP marks. In addition, the Rays defense ranks 8th this year in UZR/150, which is still pretty good, but not nearly as good as last year.

Hellickson’s strong SwStk% from last season did not translate to much of a strikeout rate spike this year and the SwStk% itself has dropped below the league average. He’s getting a bit more outside contact than the league average, which probably reduces BABIP a tad, but aside from that, his underlying metrics offer no hints whatsoever as to how the heck he has done what he has. As long as his strikeout rate remains below average, his ERA and WHIP downside are way too large to gamble that his unexplainable magic will continue. He will find himself nowhere near any of my fantasy teams next year.

Kyle Lohse

This is also the second season in a row that Lohse has significantly outperformed his SIERA. Like Hellickson, there are red flags galore. How does one only allow a .261 BABIP, yet post a 24% line drive rate? That’s crazy! His pop-up rate is also right about the league average, so that doesn’t help explain things. He is inducing a higher than league average outside contact percentage, which like Hellickson has most likely helped reduce his BABIP. Also like Hellickson, Lohse’s strikeout rate gives him little room for error, but at least he pairs his weak strikeout rate with impeccable control. Again, I need to hear some sort of statistically-backed explanation before believing Lohse suddenly has a consistent ability to significantly outperform his peripherals.

Jered Weaver

Weaver is now outperforming his SIERA for a fourth straight season, and the second in a row that he’s done so significantly. We know that Angel Stadium is a pitcher’s park that depresses home runs, and sure enough, Weaver has posted a lower HR/FB ratio at home than on the road in 6 of his 7 seasons. Also, as an extreme fly ball pitcher who regularly sits among the leaders in FB%, he is able to post well below league average BABIP marks. All those fly balls typically lead to a high IFFB% as well. Unfortunately, this year has been a bit different. His line drive rate is up above 21%, his IFFB% suddenly below the league average, and his FB% is at a career low. So of course, his BABIP sits at the second lowest mark of his career. His velocity has been on a steady decline all season, his strikeout rate and SwStk% are both down, and he has suffered from a sore shoulder from a comebacker and biceps tendinitis. Given another season of outstanding surface stats, he’ll be another name to avoid on draft day as there will be little room for profit.

Ross Detwiler

In his first full season as a starter, Detwiler has been quite the pleasant surprise for the Nats. Under the surface though, things don’t look as dandy. A fortunate HR/FB ratio and BABIP has allowed him to post an ERA just above 3.00 despite some soft skills. While the 16.8% LD% has likely helped to keep his BABIP down, his IFFB% is right at the league average and a strong GB% should also serve to inflate his BABIP. However, Detwiler has done a great job getting hitters to make contact with his pitches outside the zone. That assumed weak contact plus the low line drive rate have probably been more than enough to offset the high ground ball rate, but it’s hard to believe he would come close to repeating a .267 BABIP again. The GB% spike is good to see, but given his previous ground ball rates, it is more likely to regress a bit next year. As has been the theme for so many of these pitchers, a poor strikeout rate limits his fantasy ceiling and makes him someone to avoid.

Aaron Harang

After underperforming his SIERA for four straight years in Cincinnati from 2007-2010, Harang has finally benefited from some good luck for a change, now having pitched in much better environments over the last two seasons. This year though, his control has been uncharacteristically poor, as he has posted his highest walk rate since his rookie year in 2002. That has pushed his SIERA to a terrible 4.79. Amazingly, this is only the 2nd year of his 11 year career that his BABIP has dropped below .300. He’s doing it despite an above league average LD%, with the help of a strong IFFB%. He has also induced outside contact at a career high rate. However, with the worst F-Strike% since 2003, a career worst SwStk% and a strikeout rate that refuses to jump back above the 7.0 plateau, he’s not someone you want to bother with.


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