I think 2011 we will have to see. Even with federers serve I don't want to give Nole a definite win.
2021 possible but his problem was his injury/fatigue so not so sure.
2015 is interesting. I never thought Nole served bad in the match but who knows. Maybe.
Those are all fair points. But consider this:
2019: Med won 40.2% of his return points on hard courts that year. That is incredible. Here are his worst RPW% matches that year on hard courts.
1. 21.6% vs Kyrgios in Washington, a very fast surface for hard courts. It's rated level 4(5 is the fastest).
2. 22.2% vs Zverev in Turin; the court that Med complained was the fastest.
3. 22.9% vs Fed on the very-slow Miami court(level 2, where 1 is the slowest). By comparison, Med won 24.3% of his return points vs Opelka on that slow Miami court.
As for Djoker in 2019, here are Med's return point win% that year against Djoker:
AO: 34.9%
Cinci: 30.4%-very fast hard court, far tougher to return serves here vs Miami.
Med vs Djoker in 2021 on hard courts, RPW%
AO: 32.1%. Djoker's ace% was 3.8% vs Med
Paris Masters: 37.2%. Djoker's ace% was 7.0%.
USO: 38.0%. Djoker's ace% was 6.5%.
Fed's ace% was 10%+ in all 3 matches that he faced Med on hard courts from 2018-19.
Djoker's ace% ranged from 3.6% to 8.7% vs Med on hard courts, in 13 tries(6 times, was less than 5%)
And Fed was declining each year. Med didn't get 2015-2017 Fed.
Fed's 1st serve win% by year
2015: 80.6%; despite facing Djoker 6 times, Stan twice, and MuryGOAT once.
2016: 80.4%
2017: 79.2%
2018: 78.9%
2019: 78.1%
Djoker with 2015 Fed's serves would have been banned permanently from the ATP. He'd probably win 85% of his first serves, given his ridiculous ground game to back it up. That's just serving. Toss in the best return game in history and yeah, I see 3 CYGS.