He's a good prospect, and a good bet to make the NHL, but he just isn't what I expected him to be three years ago. I saw him play a couple times live in 2001-02, and he was the best 16 y/o defender I've ever seen in the WHL ... Wade Redden was the only guy I can remember in the same league at that age.
One game in particular was in November 2001 when he had all of about 15 WHL games under his belt. Lethbridge's top defender Simon Ferguson was out with an injury, and Seabrooke played close to 30 minutes, picked up a couple assists and was absolutely dominant. Played with so much poise, and just seemed to control the game whenever he was on the ice. At the time I felt he was a sure-fire top-5 pick for the 2003 draft. But he just hasn't seemed to develop much since, and hasn't really taken his game to the level it looked like he was capable of at that time. Intensity seems to be a common criticism.
He still has enough size, strength, poise and puck skill, though, to develop into a quality top-4 NHL defender.