For the last year-plus I have seen many people talk about why James Posey was important in our championship drive. And in my opinion, most of the takes that I have seen on that subject were wrong. Posey's main importance was NOT that he was a great defender (in fact, my eyes and the stats told me that he was only adequate at best as a swing defender) and it wasn't even that he was a veteran back-up SF to take pressure off PP (that was nice, but of lesser importance IMO).
No, Posey played two absolutely crucial roles for the Celtics:
1) He was a vet with a championship ring. KG, Pierce and Allen could run the ship for the most part due to their accolades/experience, but having the vet there with actual hardware was the last missing link to ensure the strength of the Cs' conviction through hard times. Of course, after The Cs won in '08 Posey was no longer needed for that particular role. Which leaves his other, even more important function as something we really missed last season:
2) Posey allowed the team to play great small ball. That was absolutely crucial. The Cs already had the best starting 5 in the NBA, but with Posey in the fold they were able to completely change their look in certain situations while maintaining the high quality. Against any team not featuring Shaq or Howard, KG could man the center position and dominate the middle/clean the glass, and Posey was big enough to keep most power forwards honest on defense. Then, at the other end of the court, the Celtics could field a line-up with 5 guys that could shoot at a high clip out to at least 20 feet and 4 guys that could drain the trey. The ability to run that line-up out there is a matchup nightmare for most opponents, and was a key reason the Cs were never out of any game. The huge comeback in game 4 of the Finals can be traced directly to that small ball line-up.
Now, that said, let's bring it to today. Many of those that are still looking for a Posey replacement are looking at back-up SFs as the way to do it. That is a possibility, I guess, but right now rumors are suggesting we might have a chance at the ultimate Posey replacement: Rasheed Wallace. Sheed is like an updated, upgraded version of Posey that would make this team incredibly hard to beat. Because he brings all of Posey's key small-ball strengths to the table but at a higher clip. He has Posey's shooting range and ability to take a key shot but is a MUCH better big-man defender. He also has a ring and an attitude that always makes his teammates love him and his opponents hate him (much like Posey).
I have been trying not to get my hopes to high that we get Sheed, and I will continue to try to minimize the possibility in my head so I don't end up disappointed if we miss out. But if we do get Sheed, I think he absolutely gives us everything we missed from Posey and then some in prep for the next title run.