Not sure why people are talking about Chychrun here, but in any case the fact the Coyotes decided to give him an NHL spot says a lot more about them--namely that their defensive depth is genuinely atrocious and that they aren't afraid to try out young players (instead of fishing for bargain-bin free agents in September), which a lot more teams should be doing--than it does about him as a prospect. Not sure why it's being used as evidence about his development curve. He performed exactly as you'd expect a good prospect thrust into the NHL on a terrible team to perform in his rookie year, which is to say he was pretty average, if not slightly worse than that. He ate up ice time because someone had to, but on virtually any other team he wouldn't have gotten a sniff of the NHL that year (because the other terrible teams would have just sent him down and signed an ageing veteran to a one-year deal, as I said).
That said, while I like Cholowski more in terms of playing style and awareness, I do think Chychrun was obviously more prepared to step into the NHL in their D+1 year. I think most of that was physical, but really, until Cholowski is in the NHL there's no basis for comparison... hence, again, my confusion as to why Chychrun is being discussed here.