?? You mean when boxing devolved? Would say when Lennox Lewis retired. There is a reason he is called the last great heavyweight.
I still think there is room for small incremental improvements. I can't think of any specific area mind you, but I'd like to think we haven't quite reached the absolute apex yet.
I think when fighters stopped fighting as often, and there were less and less true teachers in boxing. The 70s and 80s of course closed-circuit then cable was becoming more prominent but there will still greats although perhaps not in the abundance of prior eras. Now, in 2021, there’s almost no great teachers, fighters barely fight, and politics (and fighters let’s face it) stop the best fights thus meaning the talent can’t blossom. A lot more strength and conditioning coaches today that know a little bit about boxing, but very little real teaching of technique I feel.
There will always be ebbs and flows - but overall, I see no great improvement in boxing technique over the last 80 years (since the 1940s) or so.
There must have been something that SRR learned fighting as often as he did, having 5-6 fight series' against some other greats, that can't be learned any other way. On the other hand there have been enormous advances in how to train an athlete in general using film studies, nutrition, biomechanics, etc. Hard to say which trend would win out, unless someone invents a time machine.
It's an interesting question, because in some ways it does seem to have devolved, while at the same time also still evolving. No doubt, the talent pool is smaller now. Boxing is perhaps not seen as a 'way out' of the slums and ghettos as it once was. Reasons I can think of include: Higher standards of living. Even poor people don't usually live quite as badly as the really poor of 80-100 years ago. (In my opinion) Is being in poverty these days enough of a motivation anymore? The rise of gangs and drugs. There are tens of thousands of gang members all over Latin and North America. Maybe even hundreds of thousands. Gang life is glorified in many circles. It's easier to get rich quick being in a gang or peddling drugs than taking on a difficult career as a fighter. Opposition from other sports. A lot of the most gifted athletes play ball sports, and also the rise of MMA surely has made at least a significant dent. Take all the UFC fighters, and the ones cut from the UFC, and make them boxers. That's a significant influx of new talent. Also, I feel people just aren't as tough as they used to be. Learning a trade and doing hard physical graft was perfectly okay before. People could earn a good living. But now everyone wants to score a comfy office job or do something from home. It's a whole mentality shift. But that said, can you imagine if boxing really took hold in countries like China and India? Between them, I'm sure we could find literally tens of thousands of good promising fighters. But on the other hand, while I do agree that some of the old masters like Futch, Arcel, Goldman, Clancy, Steward haven't got an equivalent these days, there are still an abundance of very good trainers, and some may turn into the next Dundee. I think the actual science of training and fighting is as good as before, but the talent pool is simply smaller, for various reasons.
I think the sports popularity isn't what it use to be so some folks are thinking guys like Bud Crawford and Uysk aren't as good but the reality is that they could compete in any era. Not only do they have the advantages of modern training/nutrition but they are every bit as skilled.
I do remember steward claiming that boxing is no longer the great sport it used to be because "all the talented big men are now in the NBA!"
Technique and skill hasn't improved since the 1930s. Strength and power has improved and might continue to. Speed has improved across the board but might have plateaued now, over the last couple of decades, it's hard to say.
