Well the label of "NHL-ready" can be applied many different ways. For his supposed ceiling, I see no reason to do any more than get his feet wet. There is a big difference between what you'd call a top-4 defenseman on a cup contender and a top-4 defenseman on a team that misses the playoffs. If Corrado is ready to compete every single night, I'd like to see that in a role that befits his club-issued pedigree. Does he have the shot to back the powerplay? Can he make that breakout first pass every single time? To me, if you are a 25-minutes-a-night type of NHL-ready, you should be able to do those things on the regular. You should be able to produce points against professionals rather than simply prevent mistakes from occurring. Corrado is NHL-ready by the definition that he can buoy your team for a few games, but he should not be bumping anyone out of this lineup yet, so I think you need to try to build his play for the role you want him to eventually have, not the role he has today. He probably feels plenty rewarded with the tens of thousands of dollars he's earning in his pittance appearances so far.
By my standards, NHL-ready means you are "ready" to play against Sidney Crosby, Alex Ovechkin, Ryan Getzlaf, Corey Perry, Steve Stamkos, John Tavares, Evgeni Malkin and the like. Every team has 2-3 players that should be capable of stomping the majority of your defensemen in standard sessions. The Canucks have benefited the past 3-4 seasons by having multiple defensemen that could line up against those types of players and shut them down. Corrado isn't there yet, but he's pegged to be, so let's let him get there first.