4. Maxing Tobias Harris
Similar to Al Horford, there are a myriad of mistakes when it comes to Tobias Harris. The Sixers should have never traded for him, they should have never re-signed him, though once they signed him, they should have traded him sooner.
Unfortunately, Tobias Harris and his massive salary are still crippling the franchise. He is not a bad player, but he is not a good fit with Embiid (nor was he with Simmons). He never made sense and appears to be the result of the team panicking over Jimmy Butler potentially leaving that summer.
The Sixers were desperate for stars and Tobias Harris was having a career year with the Clippers. Despite that, he was not a star, and more so a result of being the best player on a mediocre team. Even if he were a star, the trio of Simmons, Butler, and Embiid had enough star power, and they needed a role player who could space the floor and defend. Instead, they overpaid in the trade and forced Tobias Harris into that role, which he still is not comfortable with.
In the aforementioned trade, the Sixers acquired an expiring Tobias Harris, Boban Marjanovic, and Mike Scott for Wilson Chandler, Mike Muscala, Landry Shamet, two first-round picks, and two second-round picks. On the surface, it may not seem like much, but those picks turned into Saddiq Bey, Tre Mann, Jeremiah Robinson-Earl, and James Nnaji.
Bey is the most valuable player in the trade, and with better drafting, that pick could have been Tyrese Maxey, Desmond Bane, or Jaden McDaniels. Mann is a very promising young player as well, and even if the Sixers never made those picks, they could have traded them for an actual star, not Tobias Harris.
Trading so much for an expiring deal is organizational malpractice.
This left the Sixers with the privilege to sign Tobias Harris to the worst contract in the NBA or let him walk for nothing. They should have let him leave in free agency, which speaks to how disastrous that contract is and how much they overpaid in the trade. A trade market for Tobias Harris has yet to materialize, and it led to the Sixers being unable to fill a proper roster around Joel Embiid, thus wasting his prime.
Even with the lack of a market, the team should have attached assets to dump the Harris contract as soon as the ink was dried. They did not and now Harris is on an expiring contract yet again. Hopefully, they can capitalize on the cap space that will be freed up from him if he leaves or signs on to a much lesser deal, but they must not make the same mistake twice.