This team simply isn't very good for a shallow roster 9 team league to tell you the truth. All this "you have a solid team, wait it out" chatter is basically a false sense of security. Take my suggestions or just leave it and consider me a jerk, but I'm trying to help.
(I'm assuming you meant D. Lee at 1B rather than C. Lee)
First of all, is there a bench in this league and who is on it if there is one?
Next, you need to drop Craig Biggio and find a replacement on the wire. You're probably getting killed in steals so I would try to get Julio Lugo in this spot who should be available considering your league depth, or get Ronnie Belliard and ride his hot bat until he slumps, then get Lugo or another player.
Sit tight with Beltre and Renteria, you can't really trade them for good value right now (I don't think) and you can't drop them. Your outfield is average at best for your league and it won't be easy to trade to improve it.
Now onto the pitching...
Sheets, no problem. (Gotta make up some wins elsewhere...)
Radke? Doesn't belong on a shallow team like this without a K/BB category in your scoring. Trade him if you can for a closer since most people disagree with me.
KRod and C Cordero are rocks. Don't touch them.
Huston Street does not belong in a league like this. Dump him for a starter or closer if one is available. (Turnbow, Wuertze, Borowski, Burgos are good candidates)
Sabathia will be real good this year, don't touch him.
Same with Rodrigo.
Same with Hampton.
Same with Burnett.
Astacio should be dropped and doesn't belong on this team.
Mussina should be considered trade bait for an offensive player. Target a team with a strong offense and weak pitching. You can afford to lose Mussina and people will see value from him if they need a pitcher.
Is this a Yahoo League?