Hmmm... An interesting question. As a long-time player of the APBA computer game I honestly feel you could put the Bambino at SS and not hurt your defense.

In the PB version, I have some shaky fielders and still am among the league leaders in team ERA with a W-L of 13-7. Willie Greene and Paul Molitor platoon at 3B and haven't hurt me in the least. Not that I am aware of, anyway. My team defense may come back to haunt me in the long run, as it is shaky in several spots. But in the middle (2B, SS, CF) I think my defense is adequate and that may be making the difference.

Defense counts in PB. I just don't think it takes into account the "realistic" feel of an outstanding fielder. But in a computer sim, I think this comes pretty close. I don't think you can get that feel of an Ozzie Smith in a computer sim because you just can't quantify it.

Hope this helps.
Elminster of Shadowdale