It isn't common for players to make the NHL right out of their draft year. Out of the Flames' current kids, Sean Monahan was the only one to achieve that feat. The rest of their current core took longer to reach where they now are.
This isn't a bad thing, though. Typically, only a handful of players actually make the NHL right after they're drafted. The first overall picks always do, plus a handful of others - almost always only guys chosen in the top 10.
Does Matthew Tkachuk have what it takes? Maybe - let's take a look at what players who made the NHL immediately this decade have in common.