McIlrath was the first of three first round picks who had a great 2nd half of the year. JT Miller was the second, and Brady Skjei the third. The Rangers seem to have developed a thing for guys who are climbing in the first round, as opposed to those who are sliding. Hell, you could even argue that Kreider was a climber in the second half of his draft year as well. Prior to that, the Rangers took 3 consecutive sliders in Sanguinetti, Cherepanov and Del Zotto.
He has a few things working against him. Being a project himself, losing almost an entire year of development has been pretty detrimental to him. I had him pegged as a 5 year guy at the very least, and with the Rangers in "win now" mode, he could wind up being a trade chip sooner rather than later.
The good news is he's gotten better every year. The bad news is that with each passing week, month, or season, the pressure builds for him to come in and make an impact. You can see that with the way he is scrambling around on the ice at this level. He's pretty steady in the AHL, but he looks like a chicken with his head cut off at the NHL level. That's too much of a difference to attribute it solely to "speed of play", IMO.
Time will tell, but I'd wager McIlrath breaks into the NHL with another organization.