Two decades into his coaching career and four decades into his pro hockey career, Blackhawks coach Joel Quenneville didn’t suddenly become a warm and cuddly guy with infinite patience just because there were a bunch of rookies on his team.

He still yells. Still growls. Still glowers. Still can’t stomach losing, boneheaded plays or easily corrected mistakes.

But after several years of leading veteran teams while integrating only one or two young players at a time, Quenneville has had to take a different tack this season, when he has had five or six first-year players in the lineup nearly every night. He has been as much a teacher as a taskmaster, more patient than prickly.

Labeled — perhaps unfairly — as notoriously trigger-happy with young players, Quenneville has had no choice but to give them a long leash this season and allow them time to grow, develop and learn from their mistakes.

‘‘As a coach, you’re more in the short-term business,’’ Quenneville said. ‘‘[But] you look at the development of the young guys. You keep

a progression chart on each guy, and you’re looking at how they’re evolving.’’

And it is an evolution. Very few players are able to step in and contribute instantly. Vinnie Hinostroza was a healthy scratch nine times in October and November. Ryan Hartman struggled for the first month after an injury tempered a quick start. Nick Schmaltz was sent down to Rockford for six weeks after getting two full months to prove himself. Michal Kempny, hardly a kid at 26 but still a first-year player, was a scratch nine times in a 10-game span in December.

As a result, Patrick Kane, Artem Anisimov, Artemi Panarin and Marian Hossa had to carry the bulk of the offense as the kids figured everything out.

But in victories last week against the Avalanche and Bruins, it was the rookies who did the heavy lifting. Tanner Kero had two goals and two assists in the two games, setting up both game-winners. Hinostroza had two goals to turn the tide against the Avalanche. Hartman has been playing top-line minutes. Schmaltz is back and playing solid two-way hockey. Kempny is becoming a fixture in the lineup.

In the past, those guys might have been shuttling back and forth between the Hawks and Rockford, constantly looking over their shoulder after every misstep. Not this season.

Quenneville spent more time teaching, breaking down the Hawks’ system and their opponents, early in the season. He has held more practices than usual and has added extra optional morning skates to the routine to allow the young players more time to work with

assistant coaches.

‘‘He definitely took time at the beginning of the season to do video with us every day and really [help us] improve,’’ Hinostroza said. ‘‘I feel like we’re getting better every practice, every game. It’s still ongoing. We still need to get better, and we’re just really focused on that.’’

Quenneville really didn’t have a choice. The salary cap has left holes in the Hawks’ lineup, and general manager Stan Bowman has raided Rockford’s roster in recent seasons in win-now trades. The IceHogs, who have been American Hockey League powers in recent seasons, are in last place in their division, with most of the Hawks’ premier prospects now an extra step away in juniors or college.

But that didn’t give the rookies any extra sense of security when the season began. Few foresaw so many getting such an extended chance.

‘‘There were so many young guys fighting for a couple of spots,’’ Hartman said. ‘‘You know you just had to play, focus on the little things and be responsible. Don’t get scored on when you’re on the ice. Play good defensively, and that turns into more trust and responsibility. At the end of the day, that gets you more ice time.’’

It always has been an exaggeration that Quenneville can’t stand young, inexperienced players. The fast rises of players such as Marcus Kruger, Andrew Shaw and Brandon Saad through the years are proof of that. But this season certainly has been different for Quenneville and the Hawks.

And given how far the rookies have come from October to now, the hope is the patience really will pay off in April, May and June.

‘‘We’ve had some changes of personnel over the years — turnovers after 2010, ’13, ’15,’’ Quenneville said. “This year was probably as big as any we’ve had. But it doesn’t matter how old or where they’re from, how big or how small. We have to find a way to make them better and work them into it. They’re all part of it.’’

Follow me on Twitter @MarkLazerus.

Email: mlazerus@suntimes.com