Colby Cohen was good going forward, and sometimes very good and average on defense, and not always that. Problem was he didn't always work hard enough in his own end.
Shattenkirk was always a much more complete player, and deserved 1st team AA honors more.
Cohen did make 1st team AA, and that is a fact. Whether it was completely deserved is subject to debate.
Yes, it is often numbers which drive AA honors on defense. A player like Strait, a shutdown defender without the O numbers, simply does not get the same consideration.
Cohen had the honors, numbers and size that intrigued NHL scouts. So leaving when he did was a good time for him to go, before his defensive deficiencies were really found out against better players. He made it to The Show.That he didn't stick is also telling.