Ray Allen struggled to get along with Rajon Rondo this season, according to Sports Illustrated's Chris Mannix.
Allen will be a free agent and is expected to be pursued by the Knicks, Heat and Bulls amongst others.
"I think there's no question that the relationship was strained over this year," Mannix said. "How strained is the key, and it's still a little bit unclear. There was some friction between those two. I think that could play a role in Ray's decision not to come back. Now, I agree, I think that Boston probably wasn't going to bring him back anyway, you're right, it's Avery Bradley's job and Ray isn't coming back to the Celtics to be a bench player, especially when he can be a bench player on a team that might be more likely to win a championship. But I think the relationship over the last year between Ray Allen and Rajon Rondo soured. Now, I'm not entirely clear as to how bad it got. But certainly I know that there was some legitimate, palpable friction between those two players and I think that will ultimately affect his decision in free agency."