I agree that Tommy could leave himself open, and be punished, especially against a counter puncher as good as Jones. However, I feel if Tommy fights a smart, measured fight, he has the attributes, and skills to beat Jones. Especially if Tommy is pressing the action, and coming forward throughout, where he's most comfortable.
Let's just get it straight, Hearns was so good a fighter that he was able to win titles up to 175 even if he was truly not a force he was at 147/154. Jones on the other hand was a phenom, a guy who literally tore through the 160, 168 and 175 division. If Jones has only speed advantage, I would say Tommy has a shot, but Jones has one-punch KO power as well.
If he came forward with his hands up instead of down by his waist like most long lanky boxers, then it would be a longer fight because RJJ would focus on right hands to the body ala Hill. Hearns whips his jab faster than Hill and most importantly brings it back fast so RJJ would most likely be tagged but eventually that lead hook will tag Hearns and it'll be all academic from then on.
It's not really fair to compare perhaps the most skilful light heavy against a man who was only truly an ATG up to light middle.I have a tonne of respect and admiration for Tommy,and I know he occasionaly performed well north of 154,but any ATG at 168 upwards deserves the nod in a fantasy match up. Tommy was one of those guys who always put bums on seats though because he had the potential to stiffen anyone.
Jones would hit harder and faster. He was fairly green though. Still he is too talented, too accurate, and too unorthodox to lose to Hearns who was chinny throughout his career.