Nah. you have them both learn both positions. This is what the Sox did I think with Hanley and Pedroia and a few others. Line them up in the majors based on which combo is most effective.
Agree. There's no harm if a guy can play either SS or 2B. When I was a kid, Pete Runnels and his chaw played SS and 2B. (Unfortunately, Pete could not play both positions at once.)
I'd promote Renda to Syracuse after the break. He has a couple dozen more games at Harrisburg than Difo. Renda only plays 2B, but the organization would probably be willing to bench Cutter Dykstra.
