Looking at that list, talent-wise, the OP has a good point. Unfortunately, the pieces don't fit.
Need more than spot-up corner 3's from Green and Bradley at an average clip to be a real threat and spread the floor. Right now, JET and Pierce are shooting well. The guys we have now lack that skill, so at least two of them probably won't be starters.
Rondo and Green have the most talent, and Bradley's defense is more impact than Sully's rebounding.
Rondo/Bradley/Green would require another shooter on the floor, a Ryan Anderson type, unless Green is your PF.
In any case, the likely move is a trade involving someone. Rondo and Green have the most talent and both have reasonable talent-to-contract ratios, though Green needs to continue to make a consistent impact.
Bradley and Sully are on rookie deals.
One in each group is injured, the other is a critical piece of the current (healthy, playing) lineup.
Tough call, but KG and Pierce are playing like it's worth trying to go for it this year.
All-in.