I had wondered the same thing myself and posted a forum on it a number of months ago.
There's a couple of things in your assumptions I disagree with:
1. We would not have BBD. He was part of the trade for Ray. Danny picked Pruitt with the C's 2nd rounder. I considered whether they'd have drafted Pruitt if they planned to keep Telfair. Since they still had Telfair at the time of the draft, I'm inclined to believe Danny would have still drafted Pruitt.
2. It's very unlikely we would have Green. Danny has openly stated he was looking to pick Yi if he kept the pick.
From earlier
Starters:
-Rajon Rondo
-Paul Pierce
-Yi ---> not Jeff Green
-Al Jefferson
-Kendrick Perkins
------------
Bench:
Delonte West / Vet FA or Pruitt--> Sebastian Telfair wouldn't have been kept around in all likelihood
Tony Allen / J.R. Giddens --> would have had someone much higher in the first round instead of Giddens
Ryan Gomes --->would earn minutes over Yi/ Bill Walker
Leon Powe / Brian Scalabrine
Glen Davis --> not on team probably would be filled by vet FA/ Shelden Williams --> not likely---Williams probably would have signed with a better team. Replaced by the 1st round pick they'd have had this year by not trading it for KG.
With this roster, PP starts at SF and either Delonte or TA starts at SG. There's no other SF on the team good enough to move PP to the SG.
Rondo would be more of a scorer by necessity. BBD and Powe (assuming that the injury wouldn't have happened since different circumstances would have existed at the time he was injured) would be the backup frontcourt.
This would be a .500 team. Pierce would be enough to carry them over the bottom teams but these guys wouldn't be able to beat the top level teams. The other starters would provide help for PP but not enough.