Before we get into it, it's important to note that Pronman's rankings encompass only players who have not cracked NHL lineups. This means that Montreal's ranking does not include Alex Galchenyuk or Brendan Gallagher, possibly their two best prospects. His rankings are meant to show the depth of the organization that you haven't seen, not the strength of the young players in the system.
Pronman gives the details on that here:
Once again, we are proud to bring our rankings of NHL organizations' prospect pools to you. This is done as a snapshot in time, with the knowledge that organizational strength can change significantly even based on one addition or subtraction. This is not a ranking of an NHL organization's drafting ability, or an overview of their entire U-23 strength, as the prospect definition strictly focuses on players outside of the NHL.
For our purposes, a prospect is defined as a player who has 25 or fewer regular season games played during the last NHL season, or 50 or fewer career NHL regular season games played - not the same as Calder Trophy requirements. For example, Mikhail Grigorenko and Louis Leblanc are eligible, while Beau Bennett, Nino Niederreiter, and Brett Connolly are not. The age cutoff is 26 years old, as of September 15th. If a player is in the KHL, he is not considered a prospect if he is signed past his age-22 season. For example, Evgeni Kuznetsov and Yaroslav Kosov are eligible, while Maxim Chudinov and Kirill Petrov are not.
With that, let's get into how he ranks the Montreal Canadiens:
13. Montreal Canadiens
Montreal graduated third overall pick Alex Galchenyuk and Calder finalist Brendan Gallagher, but their system remains strong and deep despite the absence of a true top-tier prospect. The Canadiens have added a lot of good prospects in their last two drafts to go along with first round defensemen Nathan Beaulieu and Jarred Tinordi. Still, 2009 first rounder Louis Leblanc struggled this season.
As mentioned, those two graduates create quite the cavernous hole to fill. I'm not entirely sure how Pronman defines a top-tier prospect, but unless he means someone who would be available only at lottery-pick range, I believe Nathan Beaulieu is as close as you can get there without being a top-tier guy, father/son fights notwithstanding.
While you may be disappointed with Montreal's ranking at first, it's important to note that the Canadiens' system remains very strong. For example, he ranked them ahead of the Columbus Blue Jackets, who are housing many high picks and cleaned up at the 2013 draft. There are also teams like the Detroit Red Wings, who have an "abundance" of good prospects because half of them are older than P.K. Subban (exaggerating, calm down Wings fans), whereas the Habs are relying mostly on players 21 or under for their depth.
This is especially impressive when you realize that Montreal traded away one 1st round pick, three 2nd round picks, and two 3rd round picks between 2008 and 2011, which likely significantly impacted the depth of the system.
We look forward to later in the summer when the Habs' top 10 prospects are released. For what it's worth, the Habs were ranked 10th last year.