My writings about baseball, with a strong statistical & machine learning slant.

Tuesday, March 30, 2010

2010 IP projections (with injury data)

I'm not very patient, so instead of making sure that I had this year's spring training DL listings up to date, I updated information for some prominent cases (ie Joe Nathan), and made sure I covered all the guys listed in these FanGraphs articles. Thank god that fantasy baseball fans care so about DL possibilities for lot and lots of pitchers :-)

My updated 2010 IP projections are here, sorted by +- from my previous projections when I take injury histories into account. I call this adjustment "inj_gain" in the spreadsheet.

As the name indicates, more pitchers gain IP than lose IP through these adjustments. In fact, the average pitcher has his IP rise from 59.8 innings to 65.1 innings. This is not actually gonna happen, but is rather a reflection of the unusually high number of players coming off of injuries in 2009. The average pitcher who was on a major league roster in 2009 spent 21.9 days on the DL. The 2005-2009 average was just over 15 days, so the trend of more pitcher injuries is going strong. Since I trained my projections on 2005-2009 data, it's not surprising that 2010 projected gains are too high. Also I'm missing some guys who will open the season on the DL, as I mentioned already. I probably got all the big names right, but pitchers who are not on the fantasy radar might be missing camp-related DL deductions.

Looking at the top of my list, here are the pitchers who stand to gain the most from my injury-based adjustments:

2009 IP
2010 proj
w/ injuries
DL days 2009
Carl Pavano
Tim Hudson
Chris Carpenter
Francisco Liriano
John Lackey
Brandon McCarthy

The projected returns of Carl Pavano, Tim Hudson and Francisco Liriano are all hard to argue with. However the adjustments for Chris Carpenter and John Lackey seem a bit excessive. Increasing their IP projections makes sense, but their non-injury projection were already pretty high, and thus did not need to go up by 60 IP. Then again, my system does not have many other examples of pitcher who missed a month of the season, and still threw many innings and were every effective. As I wrote before, my system does not take account of value (ERA, VORP, etc) when computing the injury adjustments, so it has no way of knowing that these guys are already projected to be pretty good in 2010. My hunch is that those two should project around 200 IP each.

I hadn't heard of Brandon McCarthy until I ran these numbers, but there is a nice article about him on FanGraphs. He's a young starting pitcher with a history of injuries and of giving up home runs, but is now finally healthy (and still pretty young). He's not listed on the Rangers' official depth chart, so he might start the season in AAA, but there is a good chance that he's end up in the Rangers' rotation sometime this season. Given the context, his new 143.1 IP projection is too high, but it would have been a reasonable projection if the Rangers had a hole in their starting staff.

Most of the large decreases in IP projection are for the pitcher mentioned in those FanGraphs articles above. Most of the pitchers mentioned will start their seasons on the DL, which leads to large reductions in projected IP. Unfortunately, Joe Nathan's projection goes down only to 33.7 IP, rather than to the 0 IP that will actually happen. On the other hand, the 0 IP projection for Chien-Ming Wang, the 28.3 IP projection for Brandon Webb, and the 7.9 IP projection for Brad Lidge are all too low, even though the algorithm has every reason to be bearish on these pitchers.

His injury history takes Roy Halladay down to 203.2 IP, a full 20 IP below John Lackey's new projection. That's a bit of over-compensation, but the algorithm is right to put those two in the same ballpark in expected IP. Other than that, there are no top-line pitchers taking large projected IP losses, except those who experienced recent injuries.

As you can see, the injury-based adjustments are rather crude and they often lead to estimates that over-shoot or under-shoot the mark. However I think that most of the estimates shoot in the right direction, and sometimes they are able to fix obvious problems with projections that don't use injury data. 

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