While working on my 2B rankings, I kept seeing Dustin Ackley and Jason Kipnis ranked low. The rankings were a combination of 2011 stats and ZIP preseason projections. While they both hit good in 2011, the projections seemed low. I decided to look into players that had similar rookie seasons and how they performed the next year.
I took all rookies from 1991 to 2011 that had between 150 and 400 PA and an OPS between 0.750 and 0.850. I chose to use OPS, because it is an encompassing stat that is available in the options at Baseball-reference’s Pay Index. Twenty-eight players made the list. Besides Ackley and Kipnis, two other rookies from 2011 where on it, Paul Goldschmidt and Eric Thames. In the end, I had 24 players to use in the comparison.
Of the 24 players, 21 of them saw their OPS drop in the 2nd year. Of the 3 that had their OPS increase, only Jason Giambi saw it significantly increase (0.761 to 0.836). The other two, Drew Stubbs (0.762 to 0.773) and Jay Gibbons (0.781 to 0.792), saw it only only increase by 0.011. On average, all 24 players saw their OPS go down by 0.065 (0.792 to 0.726).
If the same reduction in OPS was applied to the 4 rookies from 2011, their 2012 OPS would be the following. I have included the player with the closest average OPS from the combined years of 2009 to 2011 for comparison:
Kipnis: 0841 (Adrian Beltre) to 0.776 (Alfonso Soriano)
Goldschmidt: 0.808 (Michael Cuddyer) to 0.743 (Vernon Wells)
Thames: 0.769 (Marlon Byrd) to 0.704 (Skip Schumaker)
Ackley: 0.766 (Starlin Castro) to 0.701 (Clint Barmes)
The average drop would be rather substantial for these 4. The drop could actually be less. It could also be worse. For everyone that is hoping for greatness from Ackley, the Clint Barmes name is probably not what they are wanting to see.
The main problem with this group of players is that they are just entering the majors at an older age (age 23 and 24) than most rookies. Next season they will be 24 and 25 years old and just a year or two from their offensive peak at age 26.
I can see people being awe struck the seasons some rookies had last year. Historically, almost all of these older rookies regressed the next season. I now feel less guilty ranking the 2B rookies fairly low.