Even if Stevens did stick with Baynes as a starter, it would have lasted just 25 games. Baynes first extended time out was after he played 25 of the first 30 games. He most likely would have come off the bench to ease back into playing upon return and he was only back for like two weeks before going out for another extended time with injury, return and then have the current sprain that puts him out until the 2nd round of the playoffs.
Complain about not having that starting lineups but between Horford and Baynes injuries, that lineup was probably only good for about 20-25 games this year, at best.