What do you think of my team as-is, and how can I improve?

You could use another closer, but I wouldn't give up anyone good for an elite RP. Look for someone rated around 100 like Soriano, Capps, or Marmol. Their are several teams starting new closers this year with several changes throughout the year. Keep Soria, he will give you good stats to ist your SP but not as many SV's. Betancourt is a guy who could climb to a closers position in Cleveland.