Douglas. AJ mixes it up against everyone, Douglas would stay on his bike and box. Those double and triple jabs would not only keep him safe but pile points up. He was moving great that night. When he laid the right hand in, Ruiz would have no choice but to back up. Ruiz really found one great punch on AJ during that exchange of left hooks, if he found it on Buster... well, does Andy hit like Mike? Doubt it. Douglas would get up and go back to boxing.
Douglas via a jab beat down. Tokyo Douglas jab and movement were superb that night. Ruiz can't get inside, considering Tyson couldn't, I see no path for the snickers kid.
Douglas outboxes him, maybe even stops him down the stretch, although a points decision will probably be more likely. Ruiz can’t close the distance quick enough to get past that jab. Douglas pokes, prods, measures and outjabs Ruiz and frequently sets up the right behind it.
That fight would be a total mismatch. Douglas would land at will. Ruiz would never get away from Douglas' excellent jab. The referee likely saves a pummeled and bloody Ruiz in the late rounds.