The Boston Celtics have concerns about potential tampering on Al Horford ahead of free agency. The Celtics expected to negotiate a new deal with Horford when he opted out of his contract for the 19-20 season, but talks quickly broke down. Horford eventually signed with the Philadelphia 76ers.

"I don't know if you heard this, but the Celtics were, from what I am told, one of the teams that kind of stomped their feet about what they felt was tampering," said Brian Windhorst on The Hoop Collective Podcast. "Not with Kyrie, although that looked like it was lined up pretty far in advance, but with Horford.

"What happened with Horford, again from what I'm told, really upset the Celtics. They were thinking they were going to be able to negotiate with him. Talk to him about a new contract and all of a sudden it was like he already knew what his market was and he was out of there."

Jackie MacMullan countered that the Celtics had plenty of time to work on a new deal with Horford if they wanted to keep him.

"They were as surprised as we were that the money was available to Horford for the four-year deal they got," said MacMullan. "As you know, subsequent reporting revealed that the fourth year is not completely guaranteed because at the time, Elton Brand was getting killed for that deal. He was getting killed because the fourth year was being reported as guaranteed, but it isn't."

The Celtics similarly had a deal basically done with Kemba Walker before the start of free agency.