There is no likelyhood that he will have to move positions. Why does age 31 equate to inability to play SS at the same level? Because history has shown us that middle infielders often have to switch, or risk turning into defensive question marks. He probably won't have to switch at 31, but by 32 or 33 the likelihood increases quite a bit. Ripken waited until he was 35, but wasn't any good in the field from 32-34. Banks moved at 31. Yount moved at 29/30. Larkin had a very tough time being an everyday SS in his 30s. Tony Fernandez went from an everyday SS in his 20s to a part time 3B, part time SS, part time 2B in his 30s. All time great middle infielders make their career in their 20's, and usually take a significant step back in their 30s. It's much easier for slugging first baseman and corner outfielders to age gracefully, the demand on the body isn't as great. No wonder there was no love for nomar this offseason. BTW this is the best argument against this trade that I have seen so far.