What makes Dermott better than Gryzleck?
edit: to actually answer your question...
GAR thinks Colin Miller is a Norris candidate and that Jake Gardiner is a #1D. There are a lot of interesting insights there, but you can't understand role, and teammates and WHY with some R scripts.
Carlo has played two seasons... 1 season he saw top notch QoC pairing with Chara, the next season he was the baby sitter for Torey Krug. In both those seasons, he was a top 3 minute eater on a top 5 defensive team. His TOI on the PK is high end top pair.
Of course, just playing a lot on a good team isn't all there is to it. Carlo has been kinda just tall and soft most of his career. Good skater for his size, but super super conservative and too much of a collapser (like Julien taught him). The last few weeks of the season last year he switched to a more aggressive bent before he was injured. On the physical front, in denying zone entry and even with the puck. He will never be creative offensively, but no reason to think he can't be a 20-30 point guy if he isn't baby sitting a guy like Krug.
Things point to him being re-united with Chara this year and being told to move the puck and to not be afraid to join the rush. Bruins have been adding something new to his game every year. First top competition while being baby sat by Chara, the being the alpha dog defensively with Krug, and now trying to untap his two way game re-united with Chara.
Dermott has had a different path. He did very well last season against some very weak competition. Which is the more classic breaking in period. Bruins developed Carlo at the NHL instead of the AHL level and have had him work on different aspects of his game each season. Both teams should be excited about their young D. I just think that Carlo's physical tools give him a higher ceiling and the fact that he has played more at the NHL level leaves him more proven.
Of course, if you just want to sort D by GAR and say that Hamilton, Jeff Petry and Colin Miller are Norris contenders, there is nothing I can do to convince you.