The thing with Nash's postseasons are they were all usually tied to his injuries somehow. 2013 he had dealt with numerous injuries including a pretty good wrist injury that was never really reported on. Hartnett touched on it in his article here but it was never disclosed after the season.
Hartnett: No-Show Nash And Invisible Richards Must Make Difference For Rangers In Game 6
2014 was a struggle for him obviously but he was never the same after his concussion. It's not like he was great all season and then disappeared. The entire season was a struggle for him minus a random 10 game hot stretch in January.
2015 he had a great regular season up until I believe it was Bogosian rocked him. His playoffs that year was one of his better ones, 14 points in 19 games though everyone will get into the argument of which points "counted" and what didn't.
2016 he was probably the best forward and maybe best player though the team got destroyed in 5.
2017 he was great in the Montreal series but disappeared in the Ottawa series.
I don't know. I get the criticism of his playoffs but as a whole I look at his playoff career as bad luck in terms of burying chances (it happens across small samples), lack of a supporting superstar to go along with him, and primarily injury related struggles because when you get rocked in the head on multiple occasions or play hurt you're in all likelihood going to stay to the perimeter or not play your best. I just can't get on the guy due to the injuries especially when I saw the effort was there.