In the last four games, the current Pistons starting lineup with Cade, Ivey, Ausar, Stew, and Duren has posted:
124.5 Offensive Rating 112.7 Defensive Rating +11.8 Net Rating
Despite these solid numbers, the Pistons have lost by an average differential of 18.75 points per game in the last 4 matches.
They aren’t the issue!
Ausar at the 4 means a lot less shooting at PF, essentially just cuts two bigs out of the rotation (though I won’t miss either of them), and, though it means getting the regrettable offensive dead weight that is Isaiah (he’s just too slow to play PF) out of the starting lineup and into a position that he’s actually fit to play, the starting lineup is going to be operating at a disadvantage no matter what position he’s playing right now.
Ausar would also take a beating there, because he’s on the slight side at the moment and any team with bigger guys at the position would go out of their way to bully him wherever possible.