Think about how Nash at 38-years old, still manages to play at such a high level; 50+% from the field with 10 assists per game, in the 6th most efficient offense in the league - playing with a line-up of:
Shannon Brown
Jared Dudley
Channing Frye
Martin Gortat
+
Nash proved he could play at a high-level when playing 35+ minutes =
12 PPG on 52% shooting and 13 APG.
Keep in mind this is with a less-talented team; Phoenix had a higher offensive-efficiency + more team points per game. Suns were ranked 8th and Boston were ranked 26th (PPG) = individually, Nash did MORE with LESS and at a higher-efficiency rate. And this isn't even taking into account the man-to-man press', traps, hedges, defensive-schemes - Nash saw on the regular; that in comparison, Rondo hardly ever see at all.