I'm not sold that Green can be a starter on a Championship team. I can certainly be convinced, but I'm not sold on it yet. OTOH, he would be a great backup behind Pierce. Yes, I think Paul still "has it" and will still "have it" next year.
Bass is an excellent 6th man backing up the 4. I'm not sold on him as a starter on a contender, either.
Look, the C's need a super-star (or two). If they had *that* player with current Pierce, then Rondo, Green, Bass, any half-way decent center, and the remains of Ray Allen and KG could be a contender. Mix in deep bench players and you've got a strong contender. However, without a super-star walking through that door, I think the C's are going to fall short now...and in the future.
Get the straw that stirs the drink, then worry about filling up the rest of the glass.