All of this is right on the money. I've been a Celtics user for some years now and even as Rondo's rating has gone up, he isn't as effective in NBA2K as he is in real life.
To score inside with guards with high strength and big dunk packages like John Wall and Russell Westbrook, you often need do nothing more than :
1. Sprint to the baseline
2. make a 90-degree turn
3. pound on the turbo button and shot stick
4. profit!
In real life, Rondo and let's not forget Tony Parker, are at least as efficient inside scorers as those guys, if not more so. But their moves are nowhere near as simple to re-create in the game. In fact it's basically impossible to do many of the things Rondo does in real life, since real-life Rondo routinely invents new "animations" for himself that have never been attempted by anyone before.
And the things that work for Rondo in the game, he doesn't do in real life -- he almost never uses a spin or a hopstep when going to the rim, he relies on his acceleration and long stride to get past people. Doing spins and hops would just slow him down.
All that said, I've been determined this year to get more out of Rondo. I took him into freestyle practice mode and spent hours on various hopstep layups, up-and-unders and close-in shot fakes. The hop step will absolutely improve your ability to get into the paint. Learning that move, and when to employ it, is job number one. Using an iso move that leads to a hop step is even better, but a little trickier.
Two things Rondo is very good at in the game, are his ability to modify his shot, and his ability to pass out of a shot. Use a hop step to get into the paint and wiggle the shot stick before he commits. That will often open up a better shot OR a great passing opportunity. Sometimes you'll get the ball spiked back in your face, but less often than you might think; and you'll definitely have more success than when you just sprint for the basket and settle for shooting a contact layup.
Also, if you play longer games, the ability to get an opponent into foul trouble is also a nice bonus. I played a Mavs user who tried to guard Rondo with Jason Terry, and I put five fouls on Terry in the first half. For guys that try to go big with a Kobe or LeBron at the point guard spot, you can sometimes make them pay for it with these tactics.