Back to Bradley for a moment -- I went looking for some overall statistics and chose -- without knowing what the results would be -- PER and VORP as shown on basketball reference. I looked at shooting guards who have played more than 300 minutes so far this year. There are 38 such shooting guards with a PER better than Bradley's. Of those 38, all but one have a VORP better than Bradley's -0.6. The shooting guards who outpace Bradley include some big names like Harden, Wade, Bryant and Ginobili; some old friends like Jamal Crawford, Gerald Green, Courtney Lee, Tony Allen and Jason Terry; and some pretty marginal players like Jared Dudley, and Iman Shumpert; and teammate Evan Turner. Of course no one statistic captures everything, but these try to and I don't know what does a better job of it. According to these, there are many bench players performing better than him.
The team leaders in PER are Sullinger, Zeller (but with fewer than 300 minutes), Green and Rondo, in that order. There are 28 point guards who have logged 300 minutes and have PERs higher than Rondo's. Not very good.
The leading candidate for very good is Sullinger. There are 7 power forwards who have played 300 minutes and have a PER higher than Sullinger. That makes him #8 in a category that includes Dirk, Anthony Davis and Blake Griffin. I'd say that is very good. So yes, the Celtics do have a very good player. Finally, Jeff Green is in a similar situation, with the 8th highest PER among small forwards. I'm a little less impressed with Jeff, but the numbers are what they are. I will concede that Jeff is very good right now. So that makes two. Personally, I draw the line there right now, but Rondo can leap over it any time he wants to.