I have always envisioned this particular matchup with a resounding "splat" as Valdez connects and Hearns goes down,... A brutal puncher as that destruction of Briscoe showed...a shame Valdez didn't come along in another era, when there was a champion reigning other than Carlos Monzon.
Hmm, let's see Valdez who was 5'''9 1/2 with a very short reach of 69" would have to deal with Hearns pistons like jab, smashing right hand, movement skills, and superior reach. It would not end well for him. Valdes lost to the follow fighters, pre-Monzon. He was not that special. Ralph Palladin Pete Toro 26-11-3 Daniel Guanin 33-6-3 Juan Escobar, KO Loss Hearns wins. TKO inside 9 rounds Hello Jowcol, If Valdez was such a puncher, he would have won these matches. The Ralph Palladin and Pete Toro matches were in the USA, pre-Monzon. Hearns had a taller frame to grow into a middle weight body. He fought as high as Cruiser weight. Above and beyond that, Hearns was outboxing Leonard who had far more durability, speed, and skill in comparison to Valdez. Lucky for Leonard Angelo Dundee basically told him he had to slug it out to win.
I think Hearns would have a chance to outpoint Valdez if he kept a cool head and was able to avoid any damaging punches but that's a very big "if" Tommy didn't have the greatest chin in the world and it would only take one Valdez bomb to turn the tide. If I had to pick, I'd take Valdez for a stoppage.
Are we matching a prime Valdez with Hearns or the Valdez that was still growing and still developing? Leonard had more durability than Valdez? I don't know how your proving that one. You say its lucky Dundee told Leonard to go slug it out with Hearns but what do you think Valdez could/would do? Valdez was a tank. If he could walkthrough Bennie Briscoe's jab which was essentially a middleweight version of Sonny Liston's jab then Hearns jab isn't going to be an issue. Hearns' height and reach would be the big issues for Valdez. Not power, not skill, not speed. If Valdez couldn't cope with the height/reach hed get outpointed. If he could work his way inside (which is possible) then he hurts Hearns and likely stops him. The other factor is that Hearns would have to run and move all night long. Hearns' stamina wasn't always the best when he was being pressured and pressure is something he would have faced against Valdez.