Miles of rope in terms of, "can this guy be an effective NHL player / Top 6 forward / Top 4 defenseman?".........not, "Can this guy still be a massive superstar?" So yes - I have given guys like Juolevi, Virtanen, etc., "miles of rope" for the former, because I think those guys can still become that. Even in the case of a Virtanen, I'm not sure even sure if he'll be a Top 6 forward. I actually have him pegged to be a Raffi Torres/effective 3rd line guy, but I digress....."
Usually with superstars, you pretty much know if they have a good chance of becoming one or not after a very short time (i.e. Matthews, Laine, Hischier, Boeser, Pettersson, etc., just to name a few).
While anything is possible obviously (i.e. Bertuzzi, Naslund, Sedins'), I think it's safe to say that no one was thinking "future superstar" after seeing McCann in his first year. Again - he's still young enough to disprove that, but still......for the most part, McCann was a KNOWN commodity.
Toronto's first two picks were UNKNOWN commodities, and given where their team was slated to finish in upcoming years, it was a very high risk move on Burke's part to giving up TWO Firsts' (i.e. two UNKNOWN'S that had a relatively high chance of becoming SUPERSTARS). The trade blew up badly in Burke's face, and it could have been far worse had Boston not moved on from Tyler Seguin (SUPERSTAR) and Dougie Hamilton (SUPERSTAR)