Here's a different reading of the facts.
Amare has said previously that the Knicks are ahead of where he expected them to be. Its actually not surprising when you consider that Chandler and Fields are both way ahead of where people expected them to be, and Felton and Amare are also breaking new ground with their excellent current play. Maybe Donnie and Mike previously thought they needed Melo to become more competitive, and perhaps now they think it ll be more efficient to shore their greatest weakness rather one of their current strengths. (The new extra production that Chandler delivers these days on both defense and offense, makes Melo much less of an upgrade than he would have been previously. Along similar lines, both MDA and Amare recently indicated that they thought the current Knicks team was closer to where it needed to be now. Maybe that indirectly suggests that the Knicks don't need massive help at small forward, and instead should concentrate on shoring up their structural weakness at power forward. Chandler certainly seems to make the small forward position one of our strengths already.
Other issues include how important Amare thinks the playing of defense is for the Knicks. This is an area where Carmelo will likely be a weakness and not a strength. It seems to me that in the same way that Pau Gasol helped put the Lakers over the top, a talented big man that fits MDA's scheme may be what MDA and Donnie think is their most important future acquisition. So, I buy into the idea that Mike and Donnie don't think Carmelo is an essential piece and worth using both a max contract and giving up some Knicks' young talent. Perhaps, Carmelo has been advised that the Knicks may want to go in another direction with their team. That would help explain why Carmelo might be willing settle for the money and the proximity to NYC and give up the idea of playing for championships. It just doesn't make sense to me, that Carmelo would throw away the chance of playing with the Knicks in order to play with the Nets.
I don't believe he could be persuaded to do make this move by his agents, if the Knicks were waiting for him with open arms. The fact that Knicks fans want Carmelo is not a key factor imo. What matters is what Donnie and Mike think about whether Carmelo is the right move for the team based on where they are now. If they decided Carmelo was not the way to go, I certainly think they would find a way to get a message to Carmelo suggesting that he make other plans. I am not saying this is this is definitely what happened here. I am just saying that here is another interpretation that may explain Melo's otherwise confusing behavior concerning possibly signing with the Nets.