Big time. I like Simon a lot but taller fighters always gave him fits. Williams' size and workrate would wreck Simon's gameplan. When that happened Simon usually started to brawl and that would work against him in this fight. If Williams can handle Simon's power, especially late in the fight, he wins a decision.
Brown via KO. If Mathysse could land on Williams at will and stun him repeatedly (by simply brawling with the wide open Williams), I have almost zero doubt that Simon out lasts him and knocks him cold somewhere aorund 9-10.