Even eliminating some of the pre-fabricated opinions on age, it's really hard to equate Wimbledon 2009 Fed and USO 2023 Novak.
Firstly considering how Federer is the grass GOAT and his peak there is among the highest peaks for a player on any surface, him playing a good, though less than peak match in 2009 is easy to equate to a still great performance.
And the general dynamic of the match, with both serving very well and the baseline play emphisizing the attacking tennis supports this.
By comparison, Novak is a very good USO player, but always tendes to have his struggles there even when he plays well.
Generally speaking a well playing Fed on grass > a well playing Novak in NY, even removing any age barrier or other things.
But the true point against Med is how Roddick nearly beat Fed, while the russian gently rolled over in sets 1 and 3 and missed his biggest chance when the match was close.
Probably the crux of the argument is more down to the fact prime versions of these guys were still greatly challanged and I think you can agree with me here that those prime versions were damn fine on the court, so it goes against nature that someone is now old and yet less challanged. You would have to make an argument they retained their prime strengths and improved further on other attributes.
And there is literally plently of evidance, hundreads and thousands of tapes of matches from the past where the level from the baseline was just amazing. But watching years in a row of diminished intensity with the occasional eye-popping winners and fun points trains the eye into taking spectacular points over sustained consistency or normalizing the standard of play on the current tour.
Like Medvedev being an unfailible backboard or Thiem and Raz just outpeaking everyone when they can get their attacking game going. And then these guys play less than their A game and you realize they can be beaten at the strengths they are known for, sometimes when the big 3 version isn't quite in the zone.
I can readjust my eye to enjoy the tennis played by the current players, so it's not really a matter of not enjoying what's put in front right now, but it's still somewhat problematic when players who proved inferior by both objectives and subjective analysis get a lot of credit.
Sorry for the long and possibly disjointed comment, I kind of felt like spilling my entire thoughts-stream about this since I also made the OP on the same topic