It wasn’t all that surprising when Al Horford opted out of the final year of his contract with the Boston Celtics.

What was surprising was the fact that the C’s were not able to reach a new, more cap-friendly deal with the center, and watched him sign a four-year, $109 million deal with the Philadelphia 76ers.

Horford has stated that the decision was easy once he saw the figures of the proposed deal, although Danny Ainge has his own theory about what might have kept the 33-year-old in Boston.

But it turns out there may have been some sour grapes about Horford’s deal in Philly, with the Celtics feeling that Horford had offers in his pocket before talks with the Celtics broke down ahead of the start of free agency.

“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,” ESPN’s Brian Windhorst said on The Hoop Collective Podcast with Jackie MacMullan and Tim MacMahon. “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.”

MacMullan was quick to point out that some silly business happens everywhere in the NBA regarding free agency but noted that the C’s were surprised that Horford was able to land the deal he got.

“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 found there front court needing some bolstering with the exit of Horford and Aron Baynes, who was traded on draft night. But the C’s signed Enes Kanter, who already has proven to be a fan favorite and re-signed Daniel Theis. And of course, there is Tacko Fall, who the Celtics currently are working on a contract with.

But still, this only further fuels the rivalry between the 76ers and Celtics.

Thumbnail photo via Bob DeChiara/USA TODAY Sports Images