Fedr's return/baseline game decline lines up very clearly with his losses/wins to MC 14 - AO 16 ********, except that terrible USO 15 choke. Look at all the other matches, though:
MC 14 - Fedr unbroken, wins in 2 (breaks 3 times)
Wim 14 - Fedr breaks 3 times, but all in the 4th set when Djovak tightened up. Other than that, no breaks and nary a BP by Fedr, hence the loss. (Djovk could have won in str8s actually - he had a SP on serve in 1st set TB.)
Shanghai 14 - Fedr unbroken, wins in 2 (breaks twice)
IW 15 - Fedr breaks once, loses in 3 (broken 4 times, should've lost in str8s had Djovak not decided to throw in a quadruple fault for fun)
Dubai 15 - Fedr unbroken, wins in 2 (breaks twice)
Rome 15 - Fedr never breaks, loses in 2 (broken twice)
Wim 15 - Fedr breaks once, loses in 4 (broken four times)
Cincy 15 - Fedr unbroken, wins in 2 (breaks once)
YEC RR - Fedr broken once, wins in 2 (breaks four times, three of them in set 2 which Djoe half-tanked)
YEC F - Fedr never breaks, loses in 2
Conclusion: old ****** needed to cling to his serve at all costs to beat the younger -ovic. Even though his botting was at its peak, it's very tough to keep a clean sheet against Djokester, amazing that old fedr managed it 4 times in two years. Fed's return game was mug stuff compared to the days of youre, though, so once he was broken, he was toast, unable to break back. Excepting two throwaway sets by the ******** when he got broken thrice in each, Fedr could only break when his botting worked perfectly, otherwise if even the serve wasn't enough, then the return wasn't, either.
USO 15 was different from all others in that Federer was actually in ominous form and had a very real chance that he absolutely shyted up. That one is not an age thing, as we've seen old AA stay mentally strong and run the best HC players close - just a disgusting choke, far from the first time (though when he was younger, he'd take those to five except vs Claydal).