We know that by waiving Greene, the Celtics have gotten under the Luxury Tax line and have opened up a roster spot. Does that mean we can add one more player before the season starts? Technically it is possible, but I wouldn't hold my breath.
Countdown to camp: Invitation only - Boston Celtics Blog - ESPN Boston
After waiving the nonguaranteed contract of Donte Greene on Tuesday, the Celtics currently have 14 guaranteed contracts totaling approximately $71.2 million. The luxury tax line, which a transitioning Boston squad would prefer to stay under, is $71.748 million for the 2013-14 season. Boston can seemingly sneak a first-year, minimum contract ($490,180) under the line, but it leaves virtually no wiggle room. Now, keep in mind that Boston could sign any veteran to a nonguaranteed deal and waive them before the early January deadline when contracts become guaranteed and likely have enough savings to carry that extra body for the start of the season. This, too, would seemingly work against the invites if Boston elected to add, say, a veteran point guard to provide depth if Rajon Rondo is still rehabbing from ACL surgery.
So basically we could either sign one of the training camp invites to a rookie minimum deal, or we could sign a veteran to a non-guaranteed deal, only to waive him later (not sure what kind of quality player we could get to sign up for that plan), or we could just hold tight and run with 14 players heading into the season.
Personally, I say stick with 14 unless one of the invites really, really knocks our socks off. Keep the flexibility for whatever trades we'll eventually want to pull the trigger on. But that's just me.