Somehow Djokovic fans never apply this logic to Djokovic. According to them he was better in RG 2016 than in any of RG 2011-2015 simply because he won it.
It's the other way around. Many people claim Djokovic's opponent's level "mysteriously" dropped before facing him as if he had nothing to do with that happening.
Examples.
1- Federer plays a stellar match vs Murray in Wimbledon 2015 SF, can only gain a set in a tiebreak and saving set points to avoid losing in straights in the final against Djokovic.
2- Medvedev routines Alcaraz in the USO SF in 2023, one of the best matches in his career. Loses in straights to Djokovic in the final.
3- Federer trashes Wawrinka in straights at the USO 2015 SF. Loses in 4 without much trouble in the final.
4- Murray plays a great Roland Garros and clay season in 2016 (even beating Nadal). Loses in 4 to Djokovic in the final.
5- Tsonga plays a stellar match vs Nadal in the SF of AO 2008, his best match ever. Doesn't do much after the 1st in the final.
6- Murray in basically all of their AO finals.
7- Nadal having his best run ever to the AO final without dropping a set in 2019, had one of his worst-ever beatings in the final.
8- JMDP having a great run to the USO 2018 final, losing in straights in the final.
9- Medvedev having a great run to the final at the AO 2021, many people having him as an equal favorite, got destroyed in the final.
10- Ruud destroying Zverev and Rune to make the final in RG 2023, people saying he bent over in the final.
Regarding RG, many would say he played better in 2013 than in 2016 but lost because of Nadal. In 2012 he went to 5 with Seppi and had to save MP to Tsonga, so he wasn't better. 2011 hard to say, he didn't play the QF and lost in the SF, so he couldn't have been better winning only 4 matches. 2014 he was pretty underwhelming in the final. 2015 he had a much tougher time with Murray than 2016 and he was routined by Wawrinka so it can't be either. 2020 could be also it's outside that period, he was pretty good outside the Nadal match.