Perhaps I'm wrong, but a 7 footer with a pair should be able to manage to get one rebound in 16 minutes. By accident he should get one just by being somewhere near the basket. Maybe even a long rebound if he was trying in the least to go after it.
I might be wrong, but I believe that's 2 games in a row without a single board.
So, NO, I don't think he has grown anything.
Rebounding just isn't that simple. According to the NBA's tracking data K.O. had 3 defensive rebounding chances and 0 offensive rebounding chances in last nights game. 2 of the 3 def. reb. chances were rebounded by Celtic teammates. 1 lone chance of his was lost to the Wizards in the 4th qtr. when Mahinmi got an offensive rebound. That rebound should have been a very easy rebound for Rozier who badly mistimed his leap.
Rebounding is very dependent on your usage on the floor. Stretch bigs and big men that are asked to accept switches and defend out to the 3 point line naturally have many fewer as well as poorer quality opportunities to rebound than traditional big men do simply because they are often not in position to do so.
What truly matters is the overall results and not a singular aspect of the game such as rebounding. The advantages stretch bigs currently provide are far greater than having rebounding, space eating, offense killing big men on the floor who most of which also cannot help you defend at all on the perimeter.
Here is a surprising stat for you. With K.O. on the floor in the playoffs the C's are allowing 13.6 2nd chance points per 100 possessions to their opponents (this is a team best # among regular rotation players), the C's themselves are scoring the same 13.6 2nd chance points per 100 possessions with him on the floor. Despite being out rebounded by a large margin they are not giving up any more than they are scoring on 2nd chances.
For comparison the C's are giving up 18.1 2nd chance points with Horford on the floor and scoring 15.1 themselves, 20.5 with Amir while scoring only 10.