Some players are prodigies that do more winning than anyone else at a young age.
Some players hit their stride and perform better at a later age.
Different strokes for different folks and everyone is different.
Smart move from him. Gain some confidence on the North American hard courts by winning Montreal, but don't lose any mental edges by facing and possibly being beaten by Nolan/Fred. Goes into US Open fresh and hope for another easy draw.
There is a Big 3 and there is also a Big 4. What is so hard to understand?
The names were created for different reasons.
Big 3 = possibly the greatest three players of the Open Era ("of all time" is another debate)
Big 4 = the same 4 players (which includes Murray) that consistently made it...
I would pick 2015 RG final, as that win, as you stated, would have given him a CYGS and six straight slam titles.
A close second contender is one that you haven't listed: the 2012 RG final. That would have given him a "Nole Slam" much earlier and he would have two "career grand slams" to date...