Signing THjr isn't so bad that it deserves all of this reaction imo. He's not good enough to stop the Knicks from tanking right now so I don't qualify this as a win now move, the Knicks are likely still one of the worst teams( if not THE worst) in the league with him on it and with Melo off of it. 18 mil is a lot and a slight overpay imo, but cats just a year younger than him are making 20+ mil just because of assumed potential, so it could be way worse. THjr is a hardworking guy who improved a lot in the last couple of years an he still hasn't likely hit his ceiling. Plus he's still young, so he fits in terms of building towards KP's prime. When you're a crappy, young team the players you want to sign are the rfa's of the league;guys still young enough to peak around the same time as the rest of your draft picks, and ain't no max players who are really worth the money coming here in the next two or three years, so who do we want to save this cap space for?
If you don't like THjr as a player and don't think he has a future with the team regardless, then I understand why you be vehemently against the move, but otherwise I don't see what's so catastrophically bad about the signing.
The price