But Murray for me is an example which goes against your point Burrow, he was a guy who had to mature physically before he could compete with the big guys. It wasn't just about training it was also about growing into his body.
Another point I'd make is that increasing long rallies gives less explosive, more tactical (experienced) players an advantage. The young guys aren't competing well with the oldies, for whatever reason. I do agree with Burrow though that this generation should be working a lot harder to improve, I get the impression that many have been lazy and just expected to turn up and win futures and challengers immediately. Truth is, the ATP lower leagues are really tough to graduate from. It takes a ton of work/hard graft
Says who? He had reached his current height by the age of 19, and only began to change when he began preaching of his new 'rigorous' training regimes.
And anyway, your point of aerobic fitness being an advantage to the older players is very wrong, as I've already stated. It would only be an advantage if those older players were going beyond the call of duty and attaining VO2 max and Lactate Concentration levels to that of cyclists and runners, which is completely unnecessary in the first place. You can reach the desired values within months.