I'm not willing to concede that Al is going to be all that much different a player than he was last year. His minutes probably get managed better, but I think his overall effectiveness is going to be around the same.
Al's ability to be effective isn't based specifically on athleticism and the athleticism it does require, Horford has and should have for a couple more years at least.
For that reason, I'm not a huge fan of moving Al unless it's for a fairly clear upgrade, like maybe in the above proposed Horford for Barnes and Holmes deal with Sactown.