Yep, since Allen is gone, AB is kinda short, Pierce is slowing down ,

 Joseph at 6' 7" SF-SG  fills a need for a young sturdy fast slasher , get your own shot , go to man during last 10 sec. Like Paul P. , he is active on the boards for his size,  and Joseph can knockdown his freethrows pretty good too .

Joseph would come in handy playing teams like Philly , NY ,NY Nets, & Indy.

His skills are a unqiue set for the Celtics. We really have nobody but old Paul Pierce who played like this.  

with our top guards locked in, probably gotta choose 3 out of these 5:

Moore
Peitris
Daniels
Joseph
Dooling

if we keep 4 then we'll only have 2 true Centers in Fab & Steamer.
 
Top 7:
RR, AB, PP, KG, Bass, Green, Terry

Backup Bigs:
Sully, Melo, Steamer, JJJ

personally, I'd rather see more bigs down there...

with our top guards locked in, probably gotta choose 3 out of these 5:

Moore
Peitris
Daniels
Joseph
Dooling

if we keep 4 then we'll only have 2 true Centers in Fab & Steamer.
 
Top 7:
RR, AB, PP, KG, Bass, Green, Terry

Backup Bigs:
Sully, Melo, Steamer, JJJ

personally, I'd rather see more bigs down there...

with our top guards locked in, probably gotta choose 3 out of these 5:

Moore
Peitris
Daniels
Joseph
Dooling

if we keep 4 then we'll only have 2 true Centers in Fab & Steamer.
 
Top 7:
RR, AB, PP, KG, Bass, Green, Terry

Backup Bigs:
Sully, Melo, Steamer, JJJ

personally, I'd rather see more bigs down there...

Joseph is surely a smart players who knows how to play the game, has good size, and seems to be pretty good at everything.  

However, let's keep things in perspective.

First and foremost, this has been four summer league games.  The likes of Joe Forte, Kedrick Brown, J.R. Giddens, and Jeromoe Moiso all had their share of summer league success.  It doesn't mean it translates to the NBA game.  

Second, even if Joseph is an exception, the question I have is whether his skill set translates into being a role player on a team with a lot of deep talent.  While he may have similar agility and body control to Pierce, as a role player lucky to see 5 minutes of action, he'll likely never have a play called for him where he can show it off.  

The more important question will be whether he can do something like lock down other perimeter defenders, make the smart pass, and most importantly, knock down the open weakside jump shot.  

Maybe he can do it.  But I wouldn't bank on summer league success always translating into NBA success, particularly when most of these summer league guys are going to be asked to NOT be the man during the regular season.