I'd rather have Posey. And my guess is that B-diddy walked away from 18 million to become a Laker, not a Clipper, so I don't see Maggette settling for the MLE.
...your guess would be wrong, Davis is heading to the Clippers...
As far as Maggette goes, there are a number of reasons he's a good fit in Boston:
1. Multi-positional ability. Athletic enough to play the 2 or the 3 while strong enough to BS at the 4 situationally in a small lineup
2. Backing up both Pierce and Allen allows for around 30-36 mpg as Boston would be able to keep PP/RA at around 30-33 mpg during the regular season and could pick-and-choose between 3 players, keeping the hot-hand on the court at all times..
3. Maggette has a limited market available to him, and while he can probably get a bit over the MLE, it is very possible that those offers won't be there. Whatever is on the table, it may not be appreciably better than a 4-5 year deal at 5.8 million
4. While Posey is the proven role player, Maggette is a better value if it comes down to years...Posey makes sense for 2-3 years to support GPA, Maggette makes sense 4-5 years to supplant GPA and help Rondo...he'll be 33 in 5 seasons and would come off the books right after KG, so those extra 2 years of,(theoretical) prime count for a lot.
5. Bill Walker and JR Giddens would have a full 2-3 years to develop without being pressed into duty..they'd be injury/ineffectiveness insurance and could simply learn on the job by spending TC with the team, going to the D-league, and visiting with the team intermittently for progress reports and further instruction. THIS IS THE CELTIC DYNASTY WAY--watch, learn, prepare for transition...
Maggette isn't as good of a 3 point shooter as Posey, though he matched his percentage last year. But Maggette gets to the line and would be THE primary scorer off the bench and would have plenty of minutes available to him.