But Nadal reached more top tier finals (both clay and not clay) in 2011 than in 2010 (not looking at smaller events). So he played better than 2010 on his way to the finals but then played worse at the finals, all of them against the same guy? it seems that's a complicated explanation. Much simpler to say that he was playing as well or better but that only one player could stop him, and that was a GOATing Nole.
Lets not stop just with 2010 and 2011 and look at longer period for more telling results.
Nadal 2006-2009 vs Nadal 2011-2014 - those are the Nadals Fed competed with the most and Djokovic competed with the most.
Nadal 2006-2009 lost exactly 4 clay matches (Federer, Ferrero, Federer, Soderling). So Fed defeated him in exactly 50 % of his losses.
Nadal was 105:4 (96,3 WP in this period).
Nadal lost 24 sets in this period (0,22 per match), 10 of them to Federer (41,7 % of all sets lost) and 14 to field (0,15 per match).
Nadal 2011-2014 lost exactly 8 clay matches (Djokovic, Djokovic, Verdasco, Zeballos, Djokovic, Ferrer, Almagro, Djokovic). Djokovic defeated him in exactly 50 % of his losses.
Nadal was 115:8 (93,5 WP in this period).
Nadal lost 33 sets in this period (0,27 per match), 11 of them to Djokovic (33,3 % of all sets lost and 22 to field (0,2 per match).
Nadal 2011-2014 was clearly less dominant than Nadal 2006-2009 and not only compared to Djokovic but compared to field as well. Fed did in his period exactly as well as the rest of the field and so did Djokovic in his. Actually if we look at sets, Federer was actually better compared to field then Djokovic was in his.
So yes, Nadals level dropped. Not much but nonetheless. And this drop of level is reason why was Djokovic able to defeat him 4 times and why Nadal lost another 4 times to other players.