I made a post earlier that referenced this but here is a breakdown, using my subjective (but I believe consistent) definitions of prime. I'm not re-debating those here
Any rivalry has these phases, older player vs younger player (or more accurately, earlier emerger vs later emerger).
Pre-Prime vs Pre-Prime: even? (slight edge to earlier player)
Prime vs Pre-Prime: edge to earlier player
Prime vs Prime: even
Post-Prime vs Prime: edge to later player
Post-Prime vs Post-Prime: even? (slight edge to later player)
Often, the later emerger winds up with the career H2H edge because the Post-Prime phase is longer than the Pre-Prime phase, giving them more of a prolonged "dinosaur beating" phase to rack up wins. A good example of this is Lendl vs McEnroe, which was dead even when Mac entered his "post-prime" phase, and Lendl won 6/7.
Federer vs Djokovic
Prime vs Pre-Prime: 7-2 (7 HC, 2 clay)
Prime vs Prime: 7-7 (12 HC, 2 clay)
Post-Prime vs Prime: 8-14 (15 HC, 4 clay, 3 grass)
Post-Prime vs Post-Prime: 0-1 (1 HC)
Nadal vs Djokovic
Prime vs Pre-Prime: 10-4 (7 HC, 5 clay, 2 grass)
Prime vs Prime: 12-14 (14 HC, 11 clay, 1 grass)
Post-Prime vs Prime: 1-8 (4 HC, 5 clay)
Post-Prime vs Post-Prime: 2-1 (2 clay, 1 grass)
--- both of those basically go as you would expect
The player who emerged first had a decided edge before the other player hit their prime
When both were in their prime, it was essentially 50/50
When the earlier emerging player started to decline, the later emerging player had a decided edge.
Federer vs Nadal
Prime vs Pre-Prime: 1-3 (3 HC, 1 clay)
Prime vs Prime: 7-14 (5 HC, 13 clay, 3 grass)
Post-Prime vs Prime: 2-6 (5 HC, 1 clay)
Post-Prime vs Post-Prime: 5-0 (5 HC)
8 year primes
Fed Prime: mid-2003 to mid-2011
Nadal Prime: summer 2006 to summer 2014
Djokovic Prime: late 2008 to late 2016
So Ferrer shouldn't have been successful in his 30s because other players weren't?
