I am not completely diminishing his game, but he has some serious offensive flaws that hurts his team unless he has the perfect fit for him to play with. I'll go through some examples highlighting how Rondo is not even close to being a top 5 PG or even a top 15 player in the NBA now.
1 - His free throw shooting is absolutely abysmal. A team can intentionally foul him 10 times down the court and you are only guaranteed to return about 6 points off 20 foul shots...7 points if you are lucky. This is downright unacceptable for a starting guard or small forward in the NBA. Hell that shyt isn't even acceptable from the worst shooting centers at the foul line. You cannot defend this in any way possible, its pathetic. James Harden shoots about 10 free throws a game...if he shot like Rondo has been at the line his PPG will dip almost 6 full points or almost 500 points less over the course of a season. There have been point guards who have excelled in this league with a broken jump shot, but they can at least get to the line and consistently shoot anywhere between 75%-85% from the foul line. Rondo CAN'T, he has never come close to 70% at any point in his entire career.
2 - He isn't an offensive threat on the perimeter. I've highlighted the significant drop off in his shooting percentage since the trio of KG, Allen, and Pierce was broken up. This is no coincidence, the guy cannot be counted on in taking jump shots. Spacing and being the 4th option on the defensive gameplan is the reason his FG % was up so high during all those years playing with the HOF trio.
3 - He is a small guy, so you can't really expect him to drive to the lane night after night and hold up. If he wanted to take this approach? Look back at point #1...either way he isn't going to get it done on offense.
His biggest strength on offense? Passing the ball...of course it is. What else do you expect him to really do out there? Drive to the basket to maybe get lucky and hit 2 foul shots in a row? Take a midrange shot? Take a 3 pointer?

Of course his passing is his strength...its his ONLY offensive strength.
He is a great rebounder because he doesn't have to worry about getting the ball back once he is done with it...he is not going to get the ball back. That's the reason his offensive rebound totals are so high for someone so small. It's easier to put yourself in a position to rebound the ball when you are not expected to shoot. That's an extra 1-2 rebounds per game he grabs solely because of that fact.
On the defensive side. He is a great defender and positions himself very well to grab rebounds. His most impressive stat is that he gets about 2 steals per game his entire career and doesn't have to gamble as much to get them. He is a very good defender.
You can bring up the rings argument with Tony Parker because he is a legit threat whenever he touches the ball...Rondo is a threat to set someone up as long as they are able to cut to the basket or get away from his man to get an open look.
That's Rajon Rondo whether you want to face it or not. He is a good player that can excel if put in a very good position which he has been for many years so far in his career. This year he has been exposed. This is no shooting slump, this is Rajon Rondo and he is not a top 5 PG just because he can pass the ball to open teammates.