Unless you have a blistering high shooting percentage , offensive rebounds is the single biggest stat in the game IMO. In the old days it was the single thing that allowed teams to win championships without 35 PPG stars. The other thng about offensive rebounds is that the teams that get a lot all season long also seem to get them when they need them. Practice makes perfect. If every game you are playing for rebounding position and polishing your ability to grab the offensive rebounds when the D players have the inside position , then it stand to reason that when you really need one you have a much higher chance of getting one than the guy who doesn't even try for them all year long. Offensive rebounds are the result of hard work. Unfortunately hard work is not a big part of the NBA anymore.
Yes , Rondo's biggest problem is in his head. Not just getting into fights , etc but he totally loses his cool a lot. Without his head in the game , all the physical talent gets wasted at times.