Valdez knocks him out IMO. If he applies pressure, he knocks him out. If he counters, he knocks him out. Short of Jackson landing one of those monster bombs, he isn't winning IMO.
I don't see Jackson having the durability to win this. I think Valdez should be able to survive some big bombs and rocky moments early and then battle back to stop Jackson.
Valdez is a bit of dark horse at middle IMO, he's good enough to beat almost anyone he has a style advantage over. Guys like LaMotta and Tiger could well lose to Rocky.