Last year this was a glaring weakness, in particular in the Finals (though to be fair, that Lakers frontline makes a lot of teams struggle on the glass). We've added Shaq and Jermaine O'Neal to help out and though they've clearly had their best years in the rear view mirror, they can be an upgrade for us.
Perkins was limited by nagging injuries so there's at least some hope that he'll heal up properly and get back to boxing out and getting the ball sometime in the fall. I'm not exactly sure what to hope for with Garnett. He seems to be trending further and further away from the basket, and while that might prolong his career, it isn't going to help us gather the ball off the rim. Big Baby can box out, but he's most likely done growing (taller that is, his waist and emotional maturity are TBD).
We'll see if Pierce, Rondo, and others can pick up their perimeter rebounding game as well. They seemed to get away from crashing the boards as much last year but both are capable of moving the needle in our favor.
Bottom line, you can't score if you don't have the ball. Wait, I think Pau Gasol just got another offensive rebound against us as I typed this. Time to make rebounds a priority.