Updated

TORONTO -- When NHL Central Scouting unveiled its midterm report in January, there were three defensemen ranked among the top dozen North American skaters.

The list included No. 7 Dougie Hamilton of the Niagara IceDogs in the Ontario Hockey League, No. 9 Nathan Beaulieu of the Saint John Sea Dogs in the Quebec Major Junior Hockey League and No. 10 Ryan Murphy of the Kitchener Rangers in the OHL.

Those same three defensemen were scrutinized every which way when final voting took place this weekend to churn out NHL Central Scouting's top North American prospects.

"Nathan is a fluid skater, hard worker and reads the play well," Central Scouting's Chris Bordeleau, who specializes in the QMJHL, told NHL.com. "We thought he should have had more points than he had (45 points in 65 games), but overall he has the NHL quickness already. That's what is really important at this stage."

Hamilton, who had an exceptional season in Niagara with 12 goals, 58 points, a plus-35 rating and 77 penalty minutes, is as solid as they come along the blue line.

"I've watched Dougie in the playoffs and he was dominant," OHL scout Chris Edwards said. "He was pinning guys down and his puck movement was great. I hadn't seen the physical side of his game before, not much of it anyway this year, but he was strong all game. He set up the first goal of game on a nice cross-ice to (Ryan) Strome. He moves the puck well, is a great decision-maker and he's a top-two defensemen right now … probably will be in the NHL too."

Meanwhile, Murphy, who was Don Cherry's pick as the No. 1 overall choice last year, had 26 goals, including 14 on the power play, 79 points and a plus-22 rating for Kitchener.

"Could Ryan break the top 10 … it's possible," Edwards said. "His play on the power play is unbelievable. He's made a concerted effort to be more responsible in his own end, and he's still being used in a way where he's really effective. He's not put in situations where he has to be killing 5-on-3s and that type of stuff. He moves the puck on 5-on-5, and he's as solid as they come. He's made a solid effort to improve defensively."

Inquiring minds would like to know if these same three blueliners will remain the frontrunners when Central Scouting releases its final list on April 12? It's quite possible.

But there are a few other extremely talented prospects who might have gained some ground, such as Duncan Siemens of the Saskatoon Blades, Scott Mayfield of the USHL Youngstown Phantoms, Joe Morrow of the Portland Winterhawks, David Musil of the Vancouver Giants and 6-foot-7, 244-pound Jamieson Oleksiak of Northeastern University.

Last June, the first defenseman off the board was Kingston Frontenacs blueliner Erik Gudbranson, who went No. 3 to the Florida Panthers. Gudbranson, who was the highest-rated North American at his position according to NHL Central Scouting at the time, was the first of seven defenders taken in the opening round. Of those seven, only Cam Fowler of the Windsor Spitfires, who dropped to 13th before being taken by Anaheim, is an NHL regular this season.

"I was shocked when Fowler dropped," OHL scout Chris Edwards said. "I don't know why that stuff happens. Teams have the guys they want and when there are teams picking ahead of them and the guy they want is available, then I guess that type of thing can happen. Anaheim must be happy he's there though -- he's fitting in well out there."

Fowler, who has 9 goals and 37 points in 71 games as a rookie with Anaheim this season, was chosen 12th overall by the Ducks. He was the third defenseman drafted, behind Gudbranson and Dylan McIlrath (New York Rangers, 10th overall) of the Moose Jaw Warriors.

Here's a breakdown of the five other possible first-round defensemen (mid-term ranking precedes player):

14-Duncan Siemens, Saskatoon (WHL) -- Siemens might be the most physical of any top-tier defensive prospect. He had 38 assists, 43 points, a plus-40 rating and 121 penalty minutes in 72 games this season.

"I think Siemens is a complete package; he does everything really well and shows really good composure for a younger player and that's really important," Central Scouting's B.J. MacDonald told NHL.com. "He has good size, skates well, and has good mobility. I think that's one of the things I really like about him. He has the capability in a year or two of stepping up and playing in the NHL."

15-Scott Mayfield, Youngstown (USHL) -- The smooth-skating Mayfield had 6 goals, 13 points and a whopping 143 penalty minutes in 46 games for the Phantoms this season.

"He has very good size, he handles the puck very well and is composed," Central Scouting's Al Jensen told NHL.com. "I've seen him carry the puck from end to end. I think he's a strong skater and I like his upside. Maybe at times he was a little inconsistent this year at times, but overall when I look at the big picture, I see tremendous pro potential. He's a quiet type of defenseman and is steady, but not flashy."

16-Joe Morrow, Portland (WHL) -- Perhaps the 6-foot, 1/2-inch, 197-pounder was a bit overshadowed this season with the high-caliber of forwards playing for the Winterhawks this season. Still, Morrow finished with 40 assists, 49 points, a plus-23 rating and 67 penalty minutes.

"He might be one of the most overlooked defensemen in the draft this year because everyone is so busy watching the top forwards in Portland," MacDonald said. "He's a very smart player. He recognizes when to jump into the play and almost does it effortlessly, so that's a nice little component to his game that I think is overlooked.  He's a smart player and the puck is always on the tape. He'll surprise a lot of people in the draft."

26-David Musil, Vancouver (WHL) -- The 6-3, 200-pounder, who engaged in a pretty entertaining fight with Siemens at the Top Prospects Game in January, had 6 goals, 25 points and 83 penalty minutes in 62 games for the Giants.

"He has good size and he knows he has to be physical," MacDonald said. "He knows how to box guys out in the defensive zone and he's done that well. He's one of these guys who's not very flashy, but does a good job putting the puck on net all the time. He's very good at making that first outlet pass and, for a defenseman, with good size and good outlet pass, can play 10-15 years in the NHL."

He also has good bloodlines: David is the son of former NHL defenseman Frantisek Musil.

27-Jamie Oleksiak, Northeastern University (Hockey East) -- Despite a disappointing loss to Boston College in the conference tournament final, Oleksiak managed to have an extremely productive season. His Zdeno Chara-like frame helped play a big role in the back end for the Huskies. As a freshman, he finished with a team-best plus-13 rating and was the second-highest scoring defenseman with four goals and nine assists.

"I think he has unbelievable upside," Central Scouting's Gary Eggleston said. "Whoever gets him is probably going to hit a home run with this kid. You could be looking at a 15-to-16 year player in the League and to get a kid that size and skates that well is not common. He handles the puck well, has an excellent shot and his pass percentage completion in two games I saw was 100 percent -- he never missed. He covers a lot of ice in a very short time and it's a long trip around the outside with that wing span of his. He always has that stick out there dangling too, so he keeps the guys about eight feet away."

Follow Mike Morreale on Twitter at: @mike_morreale