Yes and no. Starling was a very good fighter, well schooled solid fundamentals. But theirs a very big leap from " very good" to "great" and that next level "ATG". Hearns was a ATG. If Hearns did not stop Starling ( which is possible, Starling was defensively very good, with a very good chin) He would pitch a shut out, behind his jab, and threat of landing that perfect right hand. Starling would be focused on survival. Not winning, Hearns by lopsided dec, or late stoppage.
A very good fight, but Hearns would have too much power for a back peddling Marlon. The Magic Man would make it a good fight for 5 rounds, but Tommy with that slick jab, sets up that crushing right hand that lands on the jaw of Starling, and out the lights go for Marlon. Magic Man does not have the punch to make Tommy fear him.
Marlon was a tough guy to knockout. I think Tommy would win a UD but it would not be a great fight. Sort of Tommy moving and jabbing and Marlon trying to land his punches, with Tommy beating him to the punch.
With that sucess he had against Tommy in that sparring session, Marlon would fight the fight of his life, but it would not be enough. Tommy by close UD.
Starling is a bit overrated. I give him virtually no chance against Tommy. Hearns would not only beat him, he might actually stop him.
I was just about to point that out. Marlon's chances don't improve when you halve the weight of the glove.