I know this may be shocking to some, but basketball players may have professional pride. Just winning a ring isn't always enough; not everyone can be Brian Scalabrine. A player might prefer starting on an average team to being a role player off the bench on a championship contender, not just because of the money but because he believes in himself and his abilities and wants a chance to prove himself.
When I look at the Celtics roster, I see (ideally) about 15 minutes per game available to back up each position. James Posey, who was playing for his next contract, was willing to come in because he could soak up minutes at three positions and get 25 mpg to show off. A guy like Rashard Wallace can take the bulk of the back-up minutes at both big men spots in a three-man rotation with KG and Perkins.
Eddie House is going to get 15-20 minutes per game. The question is where. If he plays as the point guard, then you can offer a talented swingman a chance to take the LLE for a year with 20+ mpg to win a bigger contract. Then you would have an 8-man rotation with guys like Scalabrine, Allen, and Walker filling in some of the holes. But House has some deficiencies as a ball-handler. If House is the shooting guard, where he is more of a defensive liability, then you have to find two players, since there probably aren't very many point guard/small forward players out there and anyone good who has that range of ability should command a bigger contract than Boston can offer. Since you're offering less playing time, you aren't going to attract players as good as if you could offer a swingman role.
The pool of players should theoretically tighten up if you are offering a role that will lead to 10-15 minutes because of professional pride. For the same amount of money, I suspect that any potential bench player that excites this message board would prefer to sign with another contender where they have a shot at 20+ points per game. It hurts even more that, playing behind the best starting five in the NBA, no free agent has a reasonable chance of playing his way into the starting lineup. Who wants to work in a dead-end job with no opportunity for advancement? That's why I expect Big Baby to bolt if any decent team offers him a chance to be a starter.
So it seems to me that we shouldn't be shocked if the Celtics don't land another big free agent because there's not that much they have to offer except a shot at a ring, and there are probably teams out there that can also offer a decent chance at glory plus more money and/or playing time. If the Celtics could offer more playing time, if it seemed they were willing to take minutes away from Eddie House to appeal to the pride of a swingman or combo guard, that would help. Stephon Marbury would probably be more willing to play for the vet minimum if he could be guaranteed 20-25 minutes per game and a chance to show that he might deserve one last decent contract when teams that strike out on the big free agents of 2010 are willing to gamble.
When it's all over, assuming the Grant Hill thing doesn't work out and that there aren't any veterans on their last legs and last contract willing to take a 10-15 mpg role and unable to do more than that, I think the Celtics will be paying the minimum salary for career backups on the talent level of guys like Kevin Ollie at point guard and Stephen Graham at small forward while hoping that someone out of Pruitt/Hudson/Giddens/Walker pans out or that they can find a mercenary who is bought out of his contract mid-season. This is what I expect, so anything better than that is spectacular and anything less than that low bar is failure on the part of Danny Ainge. I would prefer Ainge going with established mediocrity with no large upside who will be played over high-risk, high-reward projects. (I suppose he can have one with Swift). I'd like players who are Scal-like in their acceptance of bench status with no aspirations toward starting.
I don't think that is necessarily a bad thing, as this past season showed that the Celtics are a strong championship contender even with a weak bench so long as the starting five are healthy.