I think the Celtics will go with a lineup featuring Kyrie at PG, Jaylen, Hayward, and Tatum as the forwards/wings, and Horford at Center. They seem to do best with 3 wings on the floor and so long as they have a big body inside they can get away with it. Horford isn't ideal for that but he has been able to hold down the position quite well in Boston. That is in the East though and playing Embiid will test how good he is. They've been looking to replace him for a while, or bring in someone who is a stronger inside presence and move Horford to PF. The Celtics are overflowing with talent right now and Stevens finds a way to make it work. He has Marcus Morris playing well, and better than Markieff, while primarily playing "PF" if you had to assign a position to him. Markieff was always the better brother up until this season and it wasn't really much of a contest before either. Markieff's game hasn't declined much either but Stevens has Marcus rebounding and playing defense, which they both struggled to do here and since they've been gone.