I think it's pretty clear that he's going to have trouble against well-rounded fighters in the UFC. No insult to Israel at all, but it's common knowledge that grappling is not his thing. His wrestling is all defensive, a means of avoiding wrestling. And there's nothing wrong with that. But I think Israel is better at keeping people off of him than Alex will be, which will make for a very long and unhappy fight against someone like Whittaker.
But I don't think Alex gets enough credit for something that seems to be escaping everyone-- In the last two rounds Alex adjusted to Israel's strategy of clinching whenever he got too close. He started firing shots right down the middle which opened Israel up. This is what caused the ending combination too. When he'd clinch, he'd do a straight right or get an uppercut in there. He actually adjusted and developed a strategy to overcome something Israel probably thought would confound him.