just to play devil's advocate here, is anything GP said really that wrong. The Big 3 do make Rondo better than he is (as they would with anyone). Rondo is lucky to play with the Big 3 (as would anyone be). And more importantly, Rondo is inconsistent, tentative, lacks a complete offensive game, etc. Sure GP's tone is uncalled for, but that doesn't necessarily mean he is wrong.
I disagree with the notion that the big 3 make Rondo better. It might be true in the sense that Rondo learns a lot playing with the big 3 and it seemed like Ray took him under his wing last year. But in terms of on court performance, that's not true and the stats back it up.
Last season, when one or more of the big 3 was out, Rondo averaged something like 15 points, 5 assists and 6 rebounds. And it wasn't that small of a sample size, it was something like 15-16 games. This year, in the game that KG was out Rondo got 15 points, 7 assists, 8 rebounds and 2 steals. So statistically, Rondo has performed better when one or more of the big 3 are out.
Why would this be the case? Well, when the big 3 are playing, it forces Rondo to play off the ball a lot since the big 3 handle the ball a lot themselves. This forces Rondo to shoot a lot of jumpers which is his weaknesses even though he is wide open. When one or more of the big 3 are out, he gets to have the ball in his hands much more often and be able to penetrate and create shots for himself or others, his main strength. So the idea that the big 3 make Rondo look better is a big myth IMO. That would be true if Rondo's game was like House's where he is a great shooter but can't create a shot for himself so the big 3 have to do it for him, but it's the opposite with Rondo.