The standings stuff is a team issue, and the Knicks have lots of problems that have nothing to do with Melo, like Amar'e injuries, Felton and JR regressing into totally worthless players and being cap-strapped for the next year and a half.
That said, Melo isn't a player you can "build around" because he doesn't facilitate or distribute. He doesn't distribute because he doesn't draw double-teams, and he doesn't draw double-teams because he doesn't drive to the hoop consistently enough for assist opportunities. Players are considered "1's" are able to facilitate in some capacity, even if it's to the tune of 5-7 assists per game.
LeBron and Durant drive to the hoop about 6 times a game and shoot close to 60% on drives. Carmelo only drives to the hoop about twice a game and shoots 48% on his drives. That's where the significant difference in their games lies.
30/10 basketball is all good and everything, but 30/10 on 55%-60% driving to the hoop and adding 5-7 assists is different than 30/10 on catch-and-shoot plays and pull-up jumpers from the mid-range at 45% shooting are different things. The reason he play so well on the Olympic teams is because those teams are filled with the above-mentioned consistent penetration guys and those guys maximize what Melo can do. The question we should be asking is if we can get somebody like that and who that guy is. That's why Rondo is discussed so much.