If you go by the WP48 stat, Amare is actually the Knicks' second worst player and Carmelo is their 8th best player. Tyson Chandler is by far their best player, and is currently the second best player behind LeBron.
He's also currently ranked 2nd in PER right behind LeBron James who by most metrics is the most dominant player in the NBA. PER is a metric for player efficiency adjusted for pace and time played etc. Pretty nuts.
WP isn't really considered a credible metric in the basketball stat community. It overvalues rebounding; players such as Danny Fortson and Reggie Evans have been ranked in top 5 for WP.
http://www.thenbageek.com/teams/nyk