Final Pitcher ERA-SIERA Differential: The Potentially Overvalued

The review of the 2011 season has just begun and it is time to look at one of my favorite all-encompassing numbers, the ERA-SIERA differential. The pitchers with the largest differences between the two are likely to over overvalued or undervalued in fantasy leagues next season, depending on which end of the list they fell on. Today I will look at those whose ERA was most below their SIERA marks, suggesting that these pitchers may be disappointments next year.

Jeremy Hellickson

Unsurprisingly after the flurry of recent articles on Hellickson, he appears at the top of this list. If you just take his peripherals at face value, then you might expect him to massively bust next season. However, as I observed several months ago and Bradley Woodrum looked at more in depth earlier this week, Hellickson should have no problem increasing his K/9 next year, and perhaps significantly. That should offset some, though not all, of the regression his ERA will face once his .223 BABIP jumps and his 82% LOB% falls back to Earth. On strictly an ERA basis, he will disappoint many next year, but it will really depend on your league when it comes to how he is valued.

Jered Weaver

Judging by the comments from the excellent article written by Dave Cameron last week about Justin Verlander‘s 2011 performance, it is clear that what I said in my own recent article about fans getting more upset about knocking down a top pitcher, versus hyping up a lower tier hurler, is absolutely corrcet. So I get that every time I call Weaver lucky and not this good, people will get mad. But unfortunately this is reality. Of course, Weaver has outperformed his SIERA rather significantly in four of his six seasons, so it is reasonable to believe there may be something missing in the statistics we analyze. That said, he outperformed his SIERA by more than a full run this year, which was easily a career high. He has consistently maintained a lower than league average BABIP and HR/FB ratio, which does make it harder and harder to argue this is all luck. Still, if he gets drafted as a top five overall pitcher in fantasy leagues, his owners are going to be disappointed.

Ryan Vogelsong

I want to believe that most fantasy owners will immediately chalk Vogelsong up as a fluke. It is clear that he is a much better pitcher than he was when he was previously in the Majors, but an xFIP- of exactly 100 tells you that his skill set has only improved to a league average level. Pitcher half his games in AT&T Park probably helps a bit, but there’s no way he strands runners at an 80.4% clip again. With a well below average SwStk%, that K/9 is also going to fall. When you throw in the poor offense supporting him, you really aren’t left with much. He may very well drop into the reserve round in savvier mixed leagues, but he will absolutely get drafted in NL-Only leagues and is almost a guaranteed to generate a loss for his owner.

Joe Saunders

Here is a new name that I have not seen all season long and these lists. Saunders is no stranger to this type of list as he made his debut back in 2008 when he posted a surprising 3.41 ERA, despite a 4.71 SIERA. He expectedly busted the next two seasons, but he’s back again making us stat-mongers scratch our collective heads. With his pathetic strikeout rate, he really needs to exhibit pinpoint control or at least induce a ton of ground balls. Unfortunately, he does none of those, meaning that he is at the mercy of his defense. I highly doubt he gets sniffed in mixed leagues, but NL-Only leaguers tempted to take a cheap gamble thinking he won’t kill you should think again. His upside is limited by his poor strikeout potential and therefore has a much larger downside that makes him just not worth a roster spot.

Matt Cain

There he is, the list’s resident apparent lucky pitcher, who appears here on an annual basis. I was going to mention his name while writing the Weaver blurb but figured I would wait to make the comparison down here. Cain looks eerily similar to Weaver in that both are fly ball pitchers (or at least were, as Cain has finally induced more grounders than flys), display good control and typically post strikeout rates in the 7.0-8.0 range. They are even well below average in the same two luck metrics, BABIP and HR/FB ratio. Cain has been doing it about a season longer than Weaver and has outperformed his SIERA literally every season of his seven years with the Giants, six of those being full seasons. Obviously, this should no longer be considered luck, though some seasons he does get lucky and his already good HR/FB suppressing ability becomes crazy, like this year’s 3.7%. Amazingly, this is one the second season Cain’s SIERA has been below even 4.00, and the career best FB% led to his lowest SIERA mark ever. I still will probably never draft him, but he looks as safe as ever.

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Mike Podhorzer produces player projections using his own forecasting system and is the author of the eBook Projecting X: How to Forecast Baseball Player Performance, which teaches you how to project players yourself. His projections helped him win the inaugural 2013 Tout Wars mixed draft league. He also sells beautiful photos through his online gallery, Pod's Pics. Follow Mike on Twitter @MikePodhorzer and contact him via email.

17 Responses to “Final Pitcher ERA-SIERA Differential: The Potentially Overvalued”

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  1. Htpp says:

    Last year’s list would’ve had Kershaw, Jimenez, Tim Hudson, Jaime Garcia, David Price, Trevor Cahill, CJ Wilson, Buchholz, and Gio Gonzalez. So, take that for what you will.

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    • Tony M. Fernández says:

      Kershaw’s BB% fell drastically the second half of last year, so it’s not as if it was unpredictable. It just takes more analysis than a simple look at season SIERA.

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      • Mike Podhorzer says:

        There have been studies done already that have found a player’s 2nd half has no predictive value for the following season. Surely you could cherry pick examples of it being predictive, but that’s all that is, cherry picking.

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      • Tony M. Fernández says:

        The point is, there was a general trend of Kershaw’s BB% decreasing with time. This explains why his SIERA has consistently gone down. Now you can argue if that trend will continue or if he has reached his peak, but my point is, looking at SIERA and ignoring the ΔSIERA, especially for an up and coming young pitcher is a very simple analysis and is not enough. Any pitcher can have a good half of a season, but if numbers are improving year upon year, this explains improvement. ERA-SIERA is fun, but it’s not the end all be all of a search for potential cheap talent.

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  2. jim says:

    i draft matt cain every year he’s available to me, regardless of the league type. he’s never going to be a fantasy star, but he’s extremely reliable and consistent

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  3. shred the gnar says:

    What about Derek Lowe and his 1.45 differential? As a Braves fan, he’s the first pitcher I thought of when I saw the title as I knew his ERA/FIP differential was pretty drastic in the second half of the season.

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  4. herve houchoua says:

    Hellickson n est pas un bon pitcher , cela nous l avions bien compris…

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