Yeah they will, because he won't get the same usage in whatever team he goes to. You aren't getting a 99 point center because unless you plan on playing him the same amount, and running your PP through him (Hint: the NYR PP runs through Panarin and Fox, better players than Miller), he's not putting up those numbers.
Miller would get slotted behind Zibanejad. He'd be the bumper on the PP. He'd be more leaned on to kill penalties. His role is different. The rangers aren't trading for a 1C, they are trading for a 2C.
You don't get Lafreniere for 1 year of a 2C. You don't get Schneider either. You could get Othmann, but he seems to be off the board. You could get Chytil. 1 and a conditional 3 (2 if ECF) are easy to add in. That would be the best package you could get for Miller.