"New York was merely an average team (at best) when Stoudemire suited up this season, but without him they've played like a plus-7.5 team per 100 possessions. By comparison, the 2012 Heat have only been a plus-6.7 team after adjusting for opponent quality -- meaning the Knicks go from being 6.7 pts/100 worse than Miami with Stoudemire in the lineup to 0.9 pts/100 better than Miami without him."
-Neil Paine of Basketball reference
I think the Knicks are better defensively with Carmelo at the 4. I don't recall Melo getting abused by opposing power forwards when Amar'e was out. But I do remember Amar'e getting abused by opposing power forwards of questionable pedigree.
In terms of rebounding, Melo is smaller but has an instinctive nose for the ball and has always been a good rebounder.
With Melo at the 4, the players who will replace him at the three (Smith, Novak, Fields) are probably going to be roughly equal to melo in terms of defense and rebounding.
Therefore, the Knicks get a net-plus on the defense and rebounding end by Stoudemire being out. And since the Knicks couldn't figure out a way to use him offensively, they won't be hurt much offensively by him not being there.
Furthermore, Chandler should be fully recovered by Thursday night. Signs point to better defense and rebounding from the Knicks in game 3.
Baron Davis will have an extra day to rest his back - a luxury he has not enjoyed pretty much all season. A more vintage Davis playing more minutes helps the Knicks - particularly with Shump out.
The Knicks have also played well at the Garden this year. The crowd will have had a couple of days to recover from the Amar'e bloodletting, and will be pumped, enthusiastic, and hungry for a win. That should help the Knicks energy level. The refs will probably be more friendly to us.
I'm sure the Heat are psyching themselves up to keep their foot on the pedal. But pyschologically, I think it's likely they let up a little.
This game's eminently winnable.