I always go back to this. My belief is that all of the 1v1 rebounding battles ultimately who wins the rebound. Yes, if the PF is lined up for the rebound, the PF-PF match-up matters the most. However, all the other match-ups contribute to who actually gets the rebound. I believe that is how they implemented "boxing out".
If true, it means that you can't just look at stats to accurately determine whether a guard's rebounding skill is worth it vs the salary that you pay for it. Because winning the rebounding battle at guard and SF, while not giving you a lot more rebounds at those positions, may ultimately make your PF and C get more rebounds at the end of the day.
Run of the Mill Canadian Manager