Again, watch him play.
#1 he doesnt have a good shot. thats a given, he's a playmaker. He could have easely 5-10 more goals.
#2 he's creating 5-8 chances a game for himself and his teamates, if you watch him play you will see his teammates are not smart or good enough to play the tik tak toe plays hes setting up or convert opportunities because most of the time they;re never ready to receive his passes because of how quick he's thinking the game, exemple 2 games ago Rehkopf, was mobilized in front of the net with his stick not even on the ice. Mesar passes him the puck Rehkopf unfortunatly was looking at the stars, puck went right through him, thats a missed golden opportunity.
Also sometimes Mesar is creating a play (all him) but he ends up being the third passer on the play so he gets no reward.
Go to the rangers board, you will notice everyone agrees the skill is there and he;'s not a good fit for them and montreal would probably keep him in laval next year.
Also i dont think some of the players in the Rangers team like him too much, i think its a situation where alot of the players there are trying to make a name for themselfs, get drafted etc and the first 2 games he produced alot probably scared them? Specially the defenders, sometimes i feel they're going out of their way not to pass him or make an extra unnecessary pass so he doesn't get a point.