Tuesday, September 28, 2010

Understanding Seasonal Context

One of the most difficult concepts to grasp in Rotisserie is how much value can change from season to season, based upon league context.

Over at Fangraphs, Mike Axisa wrote about Hanley Ramirez's season and had this to say:
A late surge had Ramirez’s season line sitting at .300/.378/.475 (.373 wOBA) with 21 homers and 32 steals before elbow issues ended his season prematurely. It’s certainly fine production, but a notch below what he had done while posting consecutive seven-plus win seasons in 2008 and 2009.
Of course, offense is down around the league, something like 4.6% (ballpark figure). Ramirez’s offensive production is down around 10-14%, so it’s not just a matter of the decline in overall offense projecting itself onto him.

This type of analysis is fine from a Wins-Above-Replacement value standpoint. But if you're playing Rotisserie, you really want to know exactly how much offense is down so that you know how much Ramirez is worth.

2010 average National League auction hitter: 10.77 HR, 45.46 RBI, 6.47 SB, 47.49 R, .266 BA
2009 average National League auction hitter: 11.4 HR, 47.65 RBI, 6.53 SB, 49.54 R, .270 BA.

It doesn't sound like a lot, but the 2009 average hitter was statistically better than the 2010 average hitter. How did this impact Hanley's value?

2010 Hanley Ramirez: 543 AB, 21 HR, 76 RBI, 32 SB, 92 R, .300 BA. 2010: $34. 2009: $33.

In 2009's context, Hanley would have been worth $1 less.

The shift from hitting to pitching has been much more significant in the American League:

2010 average American League auction hitter: 10.86 HR, 45.95 RBI, 7.07 SB, 47.63 R, .265 BA
2009 average American League auction hitter: 13.35 HR, 52.88 RBI, 7.67 SB, 54.29 R, .271 BA.

The drop for the average hitter purchased in A.L. auctions this year was precarious. Where Hanley gained a $1, it was a much more significant gain for this year's best American League hitters.

2010 Miguel Cabrera: 548 AB, 38 HR, 126 RBI, 3 SB, 111 R, .328 BA. 2010: $39. 2009: $33.

That is not a misprint. Cabrera's 2010 numbers would have been worth a full $6 less in 2009.

The same principle works in the other direction. Cabrera's 2009 (611 AB, 34 HR, 103 RBI, 6 SB, 96 R, .324 BA) was worth a mere $31 in the 2009 formula. Those stats would have been worth $36 this year.

Two elite players, two different conclusions. In the National League, Ramirez's season - while slightly better than it would have been in 2009's context - was still a downer. In the American League, Cabrera had a much better year this year than he did in 2009...even though the raw numbers are extremely similar.

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