I have my doubts on this idea of a player under contract being an asset, just due to the contract. That was the narrative around Nerlens Noel last season, but he ended up just being dumped. This off season, you can look at John Collins, a superior player to Grant. His contract did not end up being an asset that allowed ATL to do a trade to upgrade their team. They ended up with Rudy Gay. It was just a dead weight contract that was dumped for another dead weight contract.
Another issue with Grant was that he ended up a base year compensation (BYC) contract. That means it only counts 50% as an outgoing salary but the team taking him has to count it as the full value. In a larger trade, that difference gets diluted but it makes his contract harder to trade. In the end, we got the $6.2M TPE which is at least as valuable in a trade as Grant's contract. So it ended up being exactly an allocation of cap space to use in a trade. Grant's contract was never going to be able to be used for its full value.
Now if you want to argue this from a team or roster standpoint, that is fair. Right now, there would be a role for Grant. He would be the 3rd big, similar to his role at the start of last season. From this standpoint, I have no regrets that we did not keep Grant. He has some value as a bench player, but also some major limitations and possibly some lingering baggage. I feel that role can be backfilled without having to commit to a bad contract with BYC limitations on it, we'll see.