What has Al Horford been up to since he left the Celtics?
But Horford decided to test the market, and when the 76ers swooped in with a four-year, $109 million offer that the Celtics were not going to match, he was off to Philadelphia and the 76ers. By declining the $30.1 million player option , Horford could have signed a longer-term deal for less money, providing himself with some security, while giving the Celtics some flexibility. That Al Horford would opt out of the final year of his four-year deal with the Celtics in 2019 was not unexpected. It has not exactly worked out for Horford since then, but on Friday, the Celtics traded for him, sending Kemba Walker, this years No. 16 overall pick, and a 2025 second-rounder to Oklahoma City in exchange for Horford, Moses Brown, and a 2023 second-rounder. Advertisement  Al Horford spent three seasons with the Celtics. Barry Chin/Globe Staff  Often stuck in the role of defending the post in his time in Boston, he had long-stated his desire to play on a team with an established center. He would get his wish, playing alongside Joel Embiid, but his numbers dipped considerably. He averaged fewer points, shot a lower percentage from the floor and 3-point line, and his numbers at the free-throw line fell compared to 2018-19. The 76ers struggled as well, going just 13-10 with Horford in the starting lineup. He eventually started coming off the bench as the team finished the regular season as the sixth seed and drew the Celtics in the playoffs in 2020. While Horford was inserted into the starting lineup thanks in part to an injury to Ben Simmons, he struggled in the postseason, averaging just seven points in the four-game sweep for the Celtics. Things did not get much better in the offseason, as Philadelphia traded him to Oklahoma City in a draft-night deal that sent Danny Green to the 76ers and Dennis Schroder to the Los Angeles Lakers. Advertisement  His numbers improved while playing 28 games with the Thunder, averaging 14.2 points, 6.7 rebounds, 3.4 assists and 36.8 percent from the 3-point line. But in late March, Oklahoma decided to bench him in part to evaluate the rest of the roster. With two years and $53 million remaining on his deal, a buyout was not going to happen. The team needed to find a willing trade partner. Brad Stevens and the Celtics were willing to oblige. Follow Andrew Mahoney on Twitter @GlobeMahoney.