I think it was Strikeforce's lack of fore-site. I mean the math wasn't that hard, he only had 2 fights left on his contract and he needed to fight 3 fights to win the tourney. Seems like someone at Strikeforce would have made him sign an agreement to a one fight extension if he made the finals, before they let him enter the tourney. He would have been in a really good spot if he made the final and they then had to re-negotiate to get him to fight in it. Zuffa could do the math and put a halt to it right then. Showtime must have realized the problem not to accommodate Overeem. As someone else mentioned he was probably their biggest draw.