I have played Legion ball and I ave coached a kids team or 2. (I am no Joe Torre) but I do know this....You Field the best TEAM possible. A-Rod hasn't been on a winner....YET! 3rd base is more of a reactionary position, and IMO putting A-Rod or Jeter there takes away from their natural athletic abilities. Jeter moves great to his right and picks up alot of balls from there. It means he would be awesome at 2nd base. He might not have the rings and pennents Jeter has but he does have better range to his left and better leather then Jeter. Also the reason he doesn't have the rings and so on, and Texas has been perennial cellar dwellers is the TEAM around him. One player doesn't make a TEAM. Jeter has had a cast of greats around him throughout his career A-Rod hasn't.
When I say I'm thinking with my head and not my heart I want you to know this, Derek Jeter is one my favorite ballplayers and he will be until he retires. (just like the Mick, Turman, & Mattingly) But I know when someone is a better player defensively too!