Characteristic of people on here to only notice the the things that reinforce their narrative.
You talk about the line call in ‘05, but how about Federer’s serve being unusually poor that match (our esteemed poster
@Waspsting calling it one of Federer’s ‘softest-serving displays’)? Or Federer suffering from a literal heat stroke in ‘04?
Or AO 09 F being arguably Fed’s WORST serving performance in a big match (and, per TA, the 440th best out of 453 available BO5 matches in terms of first serve percentage)?
Or 06 Dubai being one of the most aberrant matches stats-wise that you’ll find (Fed’s DR was 1.25, a DR that high will win you the match 995 out of 1000 times).
Crucially, those are the only four matches they played on outdoor HC’s up until the end of 2010. And they’re not exactly representative of their abilities at or near their best.
And this stagnation you speak of was as much mental (within the confines of their match-up) as physical, at least until Fed reached his late 20s-early 30s. Wimby 08 and AO 09 were both eminently winnable matches that, in all honesty (as flippant as it sounds) would have been won if Fed had a head-strong coach that helped shore up his returning strategy (but again, even with his Godawful return tactics AND close to career-worst serving day, Fed still almost beat a peak Nadal at the 09 AO, was the better player in the first 4 sets to the tune of a 158-144 edge in points).
Nadal has gotten the better of their head-to-head but let’s not rewrite history by claiming Fed was the lucky one to not…***checks notes***…play his biggest rival less on said rivals least favourite surfaces.