Just like Corbett evolved the game, so did Tunney a step further, and he was simply the more evolved boxer than Dempsey, better balance, combinations, set ups, technique, he used feints, made his rhythm unpredictable, could adapt etc and he would’ve always have beaten Dempsey, yes Dempsey was more entertaining and goes down as better at heavyweight with more defences, but Gene Tunney was simply better.
Different styles so incomparable. However prime Dempsey was VERY quick of both hands and feet and threw better combinations than Tunney. Dempsey was akin to Louis in terms of ultra short 3-5 punch combinations. Dempseys defense was also very good. His was a swarmers defense slipping, ducking and bobbing and weaving from a crouch and always on his toes vs Tunney which was a boxers defense with jabs along with side to side movement and clinching.
I don’t think Corbett nor Tunney evolved or changed the game significantly. I think what those two fights have in common, is a flashy youngster taking the title from a washed superstar.