Nothing against the author of this scouting report, but the description of Muzzin's game is way off the mark here. I think the contention with the overrated size is that a lot of people were misled into thinking this guy was supposed to be a physical force. Take this scouting report from HF for instance:
http://www.hockeysfuture.com/prospects/jake_muzzin/
Muzzin has no glaring weakness to his game. The 6’4 defenseman is offensively sound with an accurate one-time shot and a quick release. His passing is also above average as he makes a crisp breakout pass and can jump into the offense if needed. The greatest asset to Muzzin’s game is his nasty on-ice demeanor. He demonstrates poise and willingness to take on more than one player at a time - regardless of how much bigger they may be, and is willing to drop the gloves. He is also good at taking players out of the play and clearing the front of the net.
No glaring weakness? Nasty on-ice demeanor? Good at taking out players and clearing the net? He hasn't shown any of this at the AHL level, let alone the NHL. Once again, this kid has been overrated by many. How he's rated a 7.0 C prospect baffles me.
Here are some more scouting reports that hyped him up:
http://www.hockeyprospectus.com/article.php?articleid=1390&mode=print
http://kings.nhl.com/club/news.htm?id=529411
"Based on what I've seen, he's going to be a fantastic player," Monarchs coach Mark Morris said. "He has a big, thick body. He gets around the ice very well. He has excellent stick position. He plays within himself. He makes great decisions, reading the play on both sides of the puck.
http://forecaster.thehockeynews.com/hockeynews/hockey/player.cgi?15654
Has good size for the highest level and the ability to produce points from the back end. Moves the puck well out of danger.
Where is this player that everyone was hyping up? I haven't seen him making great decisions or using his big, thick body. From what I've seen, he tries too much, he gets beat by speed, he's not physical at all, and he takes too long to make decisions on the ice. When you're thinking out there, you are going to be a step behind.
I'm not writing off Muzzin completely, but he does not look prepared to play in the NHL now and he has a long ways to go to prove he belongs.