Rondo is way too inconsistent to be the best PG in the NBA. He had three poor games in a row, followed by tonight's great effort. If he's ever going to be on CP3's level, he needs to bring it every night.
CP3 also has "bad" games. But you're right Rondo needs to be more consistent. I think because of the nature of the Celtics having 3 "bigger" stars if Rondo isn't feeling it he sometimes pulls back.
CP3 doesn't have that luxury.
Some would say Rondo pulls back due to injury. Others (including his coach) would say he's a young player who doesn't play at full speed every game. Once he gets there, he'll be in the conversation as an elite point guard.
Rondo's had the same number of bad games in the playoffs as Ray and possibly 1 more than Paul, assuming you consider getting outplayed by Salmons a good game for Paul. The only player that might have been more consistent thus far is Perk.
Ray has how many all-star seasons in his career? Also, how many times has Doc suggested that Ray was playing at less than 100% of his capacity?
Rondo is, overall, having a fabulous playoffs. However, I think people are being a little too quick to disregard the 82 games from the regular season, when Rondo was good but not great. Good young point guard? Yes. Potential future all-star? Absolutely. Best PG in the NBA? Not until he plays more consistently, over time.
Additionally, in order to be the absolute best, Rondo needs to become a better shooter. He shot 36.8% last night, and is shooting 26.8% in his last four games. (Certainly, last night we didn't need him to shoot great, and he had a fabulous game otherwise). Even more so than the shooting percentage, though, (which was overall very good this season) he doesn't have much of an outside jumper at all. He needs to add that element to his game to be considered absolutely elite.
Rondo has cemented himself among the top ten point guards in the NBA, and on any given night he can be in the top three, or even the best. However, he won't be the absolute best until he brings the same effort every night.