On the booing of Manny Ramirez:
Before Manny left, it was perceived in Boston that there was a considerable drop off in his effort. There was a lot of grumbling about him no longer wanting to be in Boston, much more than Raffy TBH. This all combined with rumors about him being forced to leave Boston because his wife wanted to get him away from another woman made the fanbase more and more frustrated with Manny being Manny. It all came to a head when the story came out that Manny shoved the travelling secretary to the ground over tickets. He gets traded to Mannywood a month later and a rejuvenated Manny starts walloping .400 for the Dodgers. The following season, he's popped for PED's and is suspended.
While he had a great run as a Red Sox, it's easy to see how the crowd wanted to boo Manny at that point. His career wasn't on a good trajectory. He hadn't made amends with the travelling secretary yet. He was a guy who forced his way out of Boston, seemingly didn't try hard while he was here, busted his ass for his next team and got caught doing PED's.
Damon had the opportunity to comeback via trade later in his career and he nixed it, if I remember correctly.