Typically at an NHL training camp, and even throughout the season, they're in the background, the worker bees putting in insane hours watching video, devising systems and debating the minutiae of the game.

They get little credit, win or lose. But have big responsibility.

So it goes for the Toronto Maple Leafs this time around, except there's an argument to be made the assistant coaches deserve more of the spotlight than anywhere else in the league.

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Only in Toronto has the head coach, Randy Carlyle, been spared while his lieutenants walked the plank, an odd bloodletting brought on by the Leafs' management-in-transition approach led by president Brendan Shanahan.

Carlyle's being evaluated, there's no question, but newcomers Peter Horachek and Steve Spott will be his left and right arms – vital in terms of his chances for success – and charged with helping overhaul how the Leafs play.

Horachek especially.

A junior star who put up 102 points with the Oshawa Generals back in 1980 but went undrafted by the NHL, Horachek logged long miles in the minors, first as a player in the IHL, AHL and Norway, and then on the other side when he became a player-coach at only 28 years old.

Fifteen years later, the NHL finally came calling, and the Stoney Creek, Ont., native settled into a role as the long-time assistant to Barry Trotz with the Nashville Predators, a team renowned for its suffocating defensive play. Hired in 2003, Horachek was a key cog in a staff that guided the low budget Preds to five seasons with 99-plus points in the next eight years.

In Toronto, he's expected to be in charge of the defence, meaning he'll play a pivotal role in attempting to right much of what went wrong for the Leafs last season.

"We're just trying to put it in now," Horachek said of the revamped defensive system, which debuted in four scrimmages at training camp on the weekend and will be aimed at reversing a trend where the Leafs have progressively been outshot more and more each season. "Getting them a little bit of exposure to it. Talking about it a little bit.

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"We're going to use these exhibition games [to get them comfortable]. We're going to go back over it and over it."

Horachek was hired only two months ago so he's had to take a bit of a crash course in Toronto's trouble spots. He watched game footage from last season. He brought some of his own ideas as well.

What helps is he has experience in attempting a similar rescue effort, as he took over behind the Florida Panthers bench in November last season. Injuries decimated their roster, the goaltending was a mess and they had one of the weaker power plays in NHL history, but Horachek's Panthers somehow became a 50-per-cent possession team over the 66 games he coached.

The Leafs, meanwhile, had good goaltending and a strong power play much of last year but were killed in large part by an awful 41.5-per-cent possession game over that same stretch.

Horachek's approach to fixing the issue sounds an awful lot like what assistant GM Kyle Dubas and the Leafs' new analytics team will be preaching: Whenever possible, hold onto the puck and make a play.

"Obviously, if you can control the neutral zone, you control the game," Horachek explained on Sunday as the Leafs readied for a stretch of five preseason games in five days. "You control the pace of the game.

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"A lot of teams don't have possession entries [into the zone]; they have to lose possession. They have to dump pucks in. On the defensive side, we worked on some concepts there. And it's the just the start of it."

So tactics will obviously be a big part of what Horachek brings. But one of his other responsibilities, along with Spott, will be in communicating those tactics – which are becoming increasingly complex in the NHL – properly.

Last season, Carlyle appeared to understand what his team's issues were but was often unable to articulate a practical solution, to either the media or his team.

One thing Shanahan learned from talking to players when he was first hired is there had been confusion over the "defensive style they played" known as the Swarm, which led to a lack of confidence in the group.

That, in turn, contributed to wiping out the coaching staff, with Horachek and Spott tabbed by management as better communicators than those they replaced.

Horachek displayed that well in his first scrum with reporters on Day 4 of camp, breaking down some x's and o's and explaining how the NHL has shifted, system-wise, the past several years.

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He credited teams such as the Kings and Bruins with knowing precisely how to stifle opponents.

"The game continually changes and morphs," he said. "The defensive schemes for teams are so good, especially the top teams. Everybody hears about a lot of different numbers and how the stats go, but they force you to play in a certain way.

"You have to find ways to work your way through it. … Definitely you have to stay up with what teams are doing and have a way to handle it."