You've got a pretty good team. But I'd keep looking at the free agents for an outfielder who's going to have a breakout season. Your 3 outfielders all have very high potential, but I doubt all 3 will live up to it - Edmunds is always injured, Sheffield hasn't been consistent the last couple years, and Burrells strike outs could hurt him.
I agree that you could use another closer - are Jimenez or Nunez available? Also keep an eye on Embree, German, and Villafuerte. But you've got good SP and a good infield. Keep an eye on the free agents for a better shortstop, but Renteria's still better than most.