keyword: almost.Also says around 2:40 "Roger's almost playing better now than he did 10 years ago, he's improving".
Look the reality is that at age 30-31 certain things begin to slow down and there is NOTHING you can do about it. Your fast twitch muscles don't fire as fast, your reaction time is a lil slower, you don't heal/recover as fast.
All this stuff has happened to Fed. He's compensated by improving his serve and maxing out his technique. But even with those improvements he can't overcome aging. You can see it in his inconsistency. His FH might have the same strength and technique but it's not as consistent. His movement is plainly a notch below what it was.
So, there u have it. His 2015 version was damn good, probably equivalent to an average ATG but not his GOAT level.