We went through the trade rumors linking the Celtics to Al Horford at the trade deadline, so it shouldn't be much of a surprise that the Celtics will reportedly make a run at him in free agency.
"But then in summer free agency, part of the reason sources tell me that Boston didn’t make an immense offer to Atlanta for Al Horford was because Horford is a free agent this summer. Boston feels like it’s got a real chance to get Horford in free agency. I think Danny Ainge’s patience is going to pay off. They’re going to get a chance to better this team, and I think the opportunity is coming either around the draft or after in free agency."
The good news is that the Celtics won't have to give up assets to add Horford. Also, because of the CBA rules, the max number of years we would be locking him up for would be four. If we had traded for him and then given him a max extension, it would have likely been for a five-year deal. He'll be 30 this summer so there's a risk that his productivity could decline by the end of his deal.
Of course, the downside to not trading for him is that you risk him going to another team or re-signing with his current club. In fact, Chris Mannix indicated on the Celtics broadcast last night that if the Hawks gave him the full 5 years, that he would likely stay there. So a lot might depend on how the Hawks feel about him for the long term.