It was a shitty trade for the Rangers no doubt, but Buchnevich was going to be traded regardless. They could not afford him at the time, and wanted to give Kakko and Kravtsov a shot at the top-6. A big mistake in retrospect, because they have tried like 10 different wingers next to Kreider and Zibanejad since he left and none have worked. But apparently separating them is out of the question, so they keep trying to find different square or triangular pieces to shove into a round hole...
Drury absolutely butchered the value for Butch, but they were not going to keep him.