I think his worst flaw was not realizing that he did not have the most dependable chin. I don't think it was a bad chin as some will say- since he was in great fights and you cannot have great fights with a bad chin. But his height and stretched out frame meant he nor anyone built like that will absorb too many big punches. But Tommy relying on his power and exciting the crowd got him some great wins and then in other situations turned on him and put him in a bad position and sort of hurt his legacy. A very good legacy with a lot of memorable fights and wins, but with some unnecessary losses. Hopefully his passion for going for the knockout and leaving himself open in some fights and the bad situations in those fights will not hurt his overall legacy too badly in years to come- which I think is a great fighter. Some of the most impressive wins on a resume. But to be honest, as one of his biggest fans I would say if his legacy has been hurt by his kamikaze and reckless attitude in some fights (with Hagler and the fights after Hagler) then he has himself to blame 100 percent. It was his fault in those fights where he had other options and he choose to try to win big and failed a couple of times when it really mattered. It could have very well gone the other way and he could have had wins, but he didn't against Ray and Marvin. Which is what hurts his legacy the most. And that was his fault. And Ray and Marvin were good, but Tommy wanted the glory and he went for it.
I believe that only an elite welterweight with a good chin and some quickness can take Tommy in deep water and wear him down. At 147 I don't think his legs were strong as they were later on at 154 when I believe he was at his very best. He looks very strong against Benitez and Duran. His legs look sturdy, his confidence looks off the this charts. At 147 he would still have a height, range and terrifying power but in a give and take battle he would be susceptible to wilting. I never saw Tommy come back and win after his legs turn to rubber.
The worst style for Tommy is a tough boxer puncher. Pure boxers, sluggers and swarmers were his prey.
Hearns would absolutely destroy him. Did you see what Frankie Randall did with the straight right against Coggi?. He bounced him off the canvas numerous times. At that was a at 140 lbs. Coggi was no Welterweight and Hearns' straight right would put him to sleep in the early rounds.
Hearns would definitely be the favorite over a lot of guys from years ago when weigh-ins took place the day of the fight. In broad terms, they tended to be naturally shorter. Guys like Basilio were 5'6." Napoles was only 5'7". Hearns feasted on shorter fighters. And Hearns, who would weigh in under 147 a couple hours before the fight, looked like a giant next to most welters he faced. When weigh-ins were pushed back to roughly 30 hours before fights, though, you started to get guys who were physically bigger - who were closer to six feet than their earlier predecessors and would enter the ring closer to 160 - competing at welter. Barkley, who is 6'1", isn't the best middleweight ever. But he was able to take Hearn's shots, and maintain his height and push Hearns back and knock him down. So did Leonard, who was 5'10". So did Kinchen, who was about the same. So, I don't know if you had to be an all-timer to necessarily give Hearns a hard time at welter. I think you just needed to be on the taller side for a welter (not 5'6" or 5"8"), fight tall (so you're closer to his height) take a good shot, maybe be more of a natural middle but you dried out to make 147 before rehydrating (so physically you were strong), and you had to have the mental fortitude to put on the pressure and walk Hearns down. I think guys like Felix Trinidad, Oscar De La Hoya might go down, but they could take Hearns' shots and keep coming. And they had the power to hurt him. (Although I'd favor Hearns over them.) There might even be some lesser champs like Aaron "Superman" Davis who fought tall and warred with guys like Breland (who could bang) who might go down but could get up and keep coming like Barkley. Or maybe even someone like Errol Spence, who fights tall and can pop. Vernon Forrest was solid and fought tall, and had problems with unorthodox guys like Mayorga but Hearns had more of a classic style. Although Forrest didn't hit very hard. Kid Gavilan fought tall and could press the action. Again, though, there's a power problem. I'm just throwing out names. But I think you have to look at welters who tended to fight tall and had grit. The shorter guys often had grit, but many of them would just be targets due to their lack of height. I don't really see anyone like Armstrong or Whitaker or Mosley having any luck at all. Hearns was certainly one of the best welters ever. No question. He beats most everyone at 147. But there was probably an under-the-radar "Barkley" out there at welter who had the style to give Hearns problems, since every fighter does.
He did survive those bouts and won. He had a bit more experience at that time. Not so green as he was as a Welterweight. In Leonard 2 he applied what he learned from the first fight. He was able to clinch a bit during the late rounds. As we know he never learned that at 147. He never had to.