Margarito and Mattys have like the same punching power Julio presence and Williams walk right through them except in the 11th round when Margarito had Williams hurt but Williams show heart in the 12th by closing the show. Could Kirkland last the full 12th round vs Margarito that fought Williams? Honestly.
And Williams is a much more better fighter since the Margarito fight. He beat two technially skilled opponents (Quintana and Philips) and knocked them out. Williams would probably knock out Kirkland too. Williams has very underrated power, and it's not just the volume, it's the speed. Because of his reach he could throw the straight left at a far distance and the opponent wouldn't see it coming.
Even though I think Tall Paul is somewhat overrated... I see him beating Kirkland like a red headed step child. Kirkland isnt very good.