Well, believe it or not, Kessler currently has a 2.0 offense +/- and a whopping 141 offensive rating. Him being on the floor does make our offense flow better instead of settling for happy threes like we've seen year after year under Quin. Same reason Rudy made our offense better with his cutting and screen setting despite being limited offensively himself.
Him being on the floor may not have prevented a pels come back and forcing OT, but the fact is we almost blew pels out of the building with him on the floor then simply threw our lead away once we took him out.