The top executives inside the Toronto Maple Leafs organization want to believe they've entered a new phase with development of the NHL team, meaning there isn't, or at least shouldn't be, a lot of room for prospects on the roster this season.

Some rookies still may emerge, but the Leafs are hoping to have a lot of their top young players spend a full season of development with the Toronto Marlies of the American Hockey League.

"The Marlies are going to get a lot younger," Dave Poulin, the Leafs' vice president of hockey operations, told NHL.com. "There will be as many as 17 entry-level contracts down there."

Here are the Maple Leafs' top 10 prospects, according to NHL.com:

1. Morgan Rielly, D: Rielly was the No. 5 pick in the 2011 NHL Draft and is coming off a season when he had 54 points in 60 games for the Moose Jaw Warriors of the Western Hockey League. He played a combined 22 regular-season and playoff games with the Marlies after Moose Jaw's season ended.

Rielly, who is listed at 6-foot-1, 205 pounds, is too young (19) to start the season in the AHL, so his only options are to play for the Maple Leafs or return to the WHL. With a strong camp, it's possible he starts the season in Toronto, giving the team time to decide if he belongs in the NHL or if he isn't ready.

The clock on Rielly's entry-level contract wouldn't start ticking until he played in his 10th NHL game. Even if he played in 10 or more games with the Maple Leafs, they could return him to Moose Jaw at any point during the season.

"It's certainly up to him," Poulin said. "We call it punching a hole in the lineup, and if that's the case, then you adjust accordingly."

The Maple Leafs aren't sure if Rielly needs to play another season of junior hockey to be ready for the NHL, but Poulin said it could benefit him to go back to the WHL and be one of the best players there.

"Particularly in this day and age, so many kids play up so often that they never get to totally dominate a certain age group," Poulin said. "I always thought the best players in the NHL were ones that knew how to take over and dominate. There's a reason Mark Messier knew how to take over and dominate a game, because he had done it growing up at different levels. A lot of skilled and talented players never really get that chance because they're always playing up.

"You always hear, 'Well, he can play at that level.' Well, playing at that level and really playing at that level are two different things. Learning how to dominate at that level is a totally different thing. I have never minded a player being able to be the best player at a certain level. That's the benefit."

2. Joe Colborne, C: The 23-year-old forward signed a one-year contract in July and is expected to push for a roster spot this fall. Colborne, who is 6-5, 213, was pointless in a combined seven regular-season and Stanley Cup Playoff games for the Maple Leafs last season, but Poulin said the coaches and executives liked how he played in two playoff games.

Colborne, a 2008 first-round pick of the Boston Bruins (No. 16), was acquired by the Maple Leafs in a 2011 trade for Tomas Kaberle. Colborne has appeared in 16 games with the Maple Leafs during the past three seasons, posting one goal and five assists. He had 14 goals and 28 assists in 65 games with the Marlies last season. He may have to move to the wing in order to make the team.

"He's had ebbs and flows and some of them are related to injury, some of them are related to growing into a big body and some are related to just getting used to playing at a high level on a consistent basis," Poulin said. "We've seen the flashes of it, but at this level it has to be all the time."

3. Petter Granberg, D: Granberg, 21, is coming to North America for his first professional season and is ticketed to play for the Marlies, but Poulin said the 2010 fourth-round pick (No. 116) definitely is on the radar to get to the NHL sooner rather than later.

Granberg, who is 6-3, 200, has played for Skelleftea in the Swedish Hockey League for the past three seasons. He played with Alexander Edler on Sweden's top defense pair and primarily behind Henrik Sedin and Daniel Sedin at the 2013 IIHF World Championship. Even when Edler was suspended from play for his knee-on-knee hit on Canada's Eric Staal, Granberg stayed on the top pair and was one of Sweden's best defensemen as the team won the gold medal.

"He is very strong, stay-at-home and very steady," Poulin said. "He had injuries last season, but he finished the year very strongly for Skelleftea. He played a prominent role. He played 10 games in the World Championship, heads-up against the other team's best line, played against Steven Stamkos, and had a really strong World Championship."

4. Frederik Gauthier, C: The Maple Leafs’ 2013 first-round draft pick (No. 21) is a 6-5, 215-pound 18-year-old. He stood out for his size at Toronto's prospect camp in July, but the Maple Leafs will allow Gauthier time to develop his skating strength and technique before thinking about bringing him to the NHL.

He's expected to return to the Rimouski Oceanic of the Quebec Major Junior Hockey League this season. He was fourth among first-year QMJHL players last season with 60 points in 62 games. He won gold with Canada at the 2013 IIHF World Under-18 Championship and is expected to compete for a roster spot on Canada's team for the 2014 IIHF World Junior Championship after a starring role at a national junior evaluation camp in Lake Placid, N.Y., in August.

"I was not in Lake Placid, but we had both pro and amateur people in Lake Placid, and not only from within our organization but from outside our organization he had a tremendous camp," Poulin said. "The buzz was two ways but chipping in offensively, big and strong and making good decisions consistently."

5. Matthew Finn, D: The 19-year-old was a second-round pick (No. 35) in the 2012 NHL Draft and likely will return to the Guelph Storm of the Ontario Hockey League for another season. He captained the Storm last season, but was limited to 41 games because of illness and injury. The 6-foot, 199-pound defenseman had 31 points in those 41 games after putting up 41 points in 68 games the previous season. He's a hopeful for Canada's World Junior team.

"He dealt with a lot of injuries last year, but he had a really good junior camp in Lake Placid," Poulin said. "He looks very, very good right now."

6. Tyler Biggs, RW: Biggs is another one of the Maple Leafs' big prospects: 6-3, 224. He's tabbed as a power forward in the NHL, but Biggs, who played in the OHL last season for the Oshawa Generals, will need time in the AHL first.

He had 53 points in 60 games with Oshawa last season, and a goal in four games with the Marlies when he got his first cup of coffee in the AHL. Unless Biggs, a first-round pick (No. 22) by the Maple Leafs in 2011, has a monster camp and forces his way onto the team, the Maple Leafs will want him to get the full pot of coffee in the AHL.

"I assume he'll start with the Marlies and he'll grow some ownership in the group," Maple Leafs director of player development Jim Hughes said. "He has to grab the bull by the horns and make his presence felt early."

7. Carter Ashton, RW: The Maple Leafs particularly like Ashton's size (6-3, 215), strength and skating ability. They think it's all NHL-level quality, but Ashton, 22, hasn't been able to find it consistently. He did not have a point and was a minus-10 in 15 games with the Maple Leafs in 2011-12. The 29th pick in the 2009 draft spent all of last season in the AHL, where he had 19 points in 53 games.

"There is an offensive upside that has been there at various levels in the past, but he's got to find it in the NHL," Poulin said. "He scored 21 goals in the AHL [in 2011-12], which is pretty good for a 20-year-old."

8. Stuart Percy, D: Percy, 20, was selected three spots after Biggs (No. 25) in the 2011 draft. Like Biggs, he's ticketed for the AHL after captaining the Mississauga Steelheads of the OHL last season, when the 6-1, 187-pound defenseman had 45 points in 68 games.

"He may very well be a better pro than he was a junior player because of poise, timing and playing with better players," Poulin said. "He stepped into the American [Hockey League] on two different occasions and looked totally comfortable. Don't get me wrong, he has to be good enough, but in the NHL everyone is where they are supposed to be most of the time and it is easier to play. Stuart is an outlet passer and very patient person who sees the ice well. If you're patient and you see the ice and no one is there to pass it to, than your strengths aren't showing.

"Particularly the way he came out of his own zone in the American league and made the pass up the middle was just an eye-opener because most young players aren't willing to have the patience to show that. So his view of the game and his patience for the game may be better suited at a higher level."

9. Josh Leivo, LW: Poulin said the Maple Leafs like the weight Leivo has put on during the past couple of years. They drafted the 6-2 left wing in the third round (No. 86) of the 2011 NHL Draft when he was 178 pounds; he's up to 198 now, according to Hughes.

Leivo, 20, will start the season with the Marlies. He put up 73 points in each of the past two OHL seasons.

"He's that prototypical power forward whose body is now catching up to the prototypical part," Poulin said. "He's put on significant, good weight in the past couple of years. He was a late bloomer in his OHL draft year, but has really emerged post that and the last couple of years has been one of the top players in the league. He plays very well down low, on the cycle, on the boards and he's kind of slippery in the way he operates."

10. Greg McKegg, C: The 21-year-old earned playing time under former Marlies coach Dallas Eakins last season. In 61 games he had eight goals and 15 assists, but most importantly he settled in at center and started to make a lot of plays that caught the eye of Poulin and other Toronto executives.

McKegg (6-foot, 191) has played in NHL exhibition games and likely will again this season, but he's most likely going to start the season in the AHL.

"We like his vision and his hands," Poulin said. "His skating has improved vastly over the last couple of years, but his hands and his hockey sense were always there. He had 270 points in 262 junior games, so he puts up numbers, but what he did is round out his defensive game for the Marlies and that earned him more playing time."

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Author: Dan Rosen | NHL.com Senior Writer