In contrast to what you might read elsewhere on the net,
in the NBA, the inability to REBOUND the basketball on a consistent basis, as a TEAM, is not a “Concentration” issue; nor is it an issue of “failing to get into [opponents'] bodies”.
At this level of competition …
A team’s ability to REBOUND successfully is a “Personnel” issue. Period.
Relative to the position they are playing:
“++” Rebounders are major contributers;
“+” Rebounders are positive contributers;
“0″ Rebounders are neither positive nor negative contributers; and,
“-” Rebounders are negative contributers.
When you look at the Raptors’ roster, this is what you see:
PG /Calderon 0
A good Rebounding team in the NBA needs to have at least three  “+” Rebounders on the court at all times.
With their current roster, the Raptors do not fit into this category … plain and simple … because:
1. Specifically, given the “+” Rebounders they DO have on this team, the Raptors are choosing to play the WRONG players in combination with one another, so far this season;
2. In general, there are NOT ENOUGH “+” Rebounders on the Raptors’ roster in the first place.
Until the Raptors fix THIS issue they will not be able to solve their Rebounding problem.