The is true, but you can argue Djokovic cost Nadal RG 15 also. We don't know for sure what would have happened if Nadal had managed to get past Djokovic. We know how lethal he is in the business end of RG.
That's seriously stretching it given the form Rafa showed in the RG, especially vs. Novak, and given how Murray and Stanimal competed vs Djoko.
At most Novak took 3 slams away from Rafa and one of them, US Open 2011, you could make the argument for Fed (I personally favor Rafa in a US Open 2010 final, but give the small edge to Fed in a hypothetical 2011 encounter) and in another, AO 2012, you could make an argument for Murray who played Djoko just as close and has beaten Rafa at the AO (and the US for that matter).
With Fed, Novak did take Wimbledon 2015 (Gasquet, no argument I presume), W 2014 (Dimi, agree I presume?), AO 2008 and 2011 (Tsonga, first time slam finalist, but Fed played Novak close in the semi and I think his experience, despite being ill, would have been enough. 2011 vs. Murray I have close to no doubt given how their slam encounters unfolded those years and apparently still do).
And then there's the questionable US Open 2011.
In total:
Rafa lost 2-3 due to Novak (0,5 + 0,5 = 1 for US Open 2011 and AO 2012)
Fed lost 4-5 due to Novak (0,5 + 0,5 = 1 for AO 2008 and US Open 2011).
Lets just agree to disagree again. Nadal stunk up the joint in 2014 also, and still walked away the RG champion. He is undefeated when he makes the title match, so I won't right him off, if he had got past Novak.
If he got past him, he would have been a massive favorite in the eyes of quite a few people. So lets just agree to disagree.
But that's a very hypothetical if. He wasn't even close to matching Novak's level. Had he beaten him, he would have been a definite favorite, but it would also have meant he had played on a level far far above anything he displayed at that tournament. So imo, you can't quite phrase it that way as that's assuming Rafa played as he can at his very best, which he was far away from
Yeah but the losses Nadal had were at his peak/prime, thus more detrimental especially after the fantastic 2010 that he had. Nadal could have won four slams in a row and would have overtaken Federer in GS count. While Federer was post prime for most of his losses against Novak, even in 08 he was sick during AO. Novak was expected to win most of those matches.
He did possibly prevent a Rafa slam though it's not clear cut because of Muzz, see above, but he took more from Fed nevertheless.