Nice squad. How deep is the league and what's the scoring format? Without knowing that, I'd still say your hitting is really good. The only area that might need work is SBs. Renteria should get a decent amount and K. Matsui might as well, though personally I'm really expecting him to be a bust this year. I don't think Vlad will run too much this year either, but the rest of the hitting stats from that lineup should be great.
Pitching-wise, you could use some help at closer. Judging from the hitters you have, I'm guessing this isn't a very deep league, probably not more than 10 teams. In that case, I would think you'd need at least three closers, especially if you're going to rely on Mantei, who's always an injury risk and is already having problems this year with his fingernails and might not close at the start of the season. If there aren't closers available and you don't want to give up anything to trade for one (or two), then look for some solid set-up guys who could steal some saves and will do a lot more to help your ERA and WHIP than a mediocre or risky starter like Willis or Harden. With your other starters, I don't see a reason to hold on to those guys unless this is a keeper league (though their name value might be enough to get you a decent closer or elite set-up guy so shop them first before dropping them). Look for set-up guys like Valverde (almost a must-have for Mantei owners), Lidge, Marte, K-Rod, etc. Good luck.
"I'm telling ya, he jumped us. Gloves off, stick down, no warning. He challenged the Chiefs. Called us names. But Dave was there."
"Dave's a killer."
"Yeah, Dave's a killer."
"Dave's a mess."