Look at the difference between the 2007 and 2008 Yankees and you can chalk up the win differential on the lack of offense. There are plenty of reasons for that, from a terrible season by Robinsn Cano to way too many AB's for Cabrera and Molina. Let's look at the current 40-man and talk about who comes back and who has to go.
Catchers: The Yankees ended the season with five catchers on their 40-man and they will cut that down to 3 immediately. Chad Moeller and Ivan Rodriguez will be allowed to depart and that leaves the team with Posada, Molina and Cervelli. Now, the Yankees will keep all three, but they need to look long and far for a better backup than Molina. Yes, Molina is wonderful with the pitchers, but he can't hit and he isn't, how should I put this, "built" to play everyday. Remember, Posada is coming to camp off of shoulder surgery. The Yankees would love him to catch 120 games next year, but that may not be realistic. The problem is, nobody will know what Posada can and can't do until he makes it to camp. Counting on him to be the regular cacther is a risky move.
Infielders: We know Jeter and A-Rod are back and beyond that you have a lot of questions. I would look around and see if there are better bench players than Betemit, Duncan and Ransom. All three of them are flawed players, but the Yankees don't have anything in the minors better right now. That will hopefully change towards the end of the year when the promising players in AA in 2008 do well in 2009, but for now the best idea is to probably just bring the three of them back and sit tight.
Juan Miranda is an interesting guy, buy I don't know his real age and he hasn't hit for enough power in the minors to give him a job out of camp.
And that brings us to Jason Giambi. There are some compelling reasons to bring Jason back, most of all his patience at the plate. But, with Posada and Matsui coming off of surgery and Giambi useless at first, the Yankees have to free up his spot and let him go. They will miss his bat, but deleting him from the roster gives them flexibility.
Outfielders: Hideki Matsui is the only lock to come back and that is because no one will take him off of knee surgery. Matsui has volunteered to bring a first baseman's glove to camp and Brian Cashman should let him. Flexibility is great and not having to use Matsui as a DH everyday would be a plus.
Damon and Nady should be back, but the Yankees shouldn't be afraid to trade either of them in the right deal. Most likely they are staying and you can pencil them in for left and right, though it should be remembered that Nady played first before.
There is no reason not to give Gardner, Christian and Cabrera another shot, though Gardner is probably the only one who can still be called a prospect. Cabrera went backwards in 2008 and it is doubtful the Yankees would get much from him on the trade market. Christian is too old to be a prospect, but his speed could help a team off the bench (assuming he learns how to avoid getting picked off)
Gardner is the most interesting guy because it is still unclear what he is. One interesting pattern with Gardner has been his tendency to struggle when he comes to a new level and then it clicks for him. He was awful in July and then hit a little bit in September. Giving him the CF job is a big risk, but the Yankees may want to take a shot. Austin Jackson is clearly the future, but he won't be ready probably until 2010. With Jackson in the system, signing or trading for a centerfielder doesn't make a ton of sense. Can Gardner handle 150 games in center? I don't know if anyone can answer that question.
Last is Bobby Abreu, who had a very nice offensive season and a terrible defensive one. Losing Giambi and Abreu from the lineup would be big losses and I think the Yankees should offer Bobby arbitration. If he accepts it, you bring him back for one year, which isnt a huge risk. (Remember Nady has played first) If he doesn't, the more likely scenario, you get draft picks. To me that's a win-win, I wouldn't do anything else lke trying to sign him to a new deal.
That's three more off the 40-man and possibly more if there are some better infield options out there. We will start talking about free agents soon.