If you watched the tail end of the Isles' season, you know exactly where Dobson struggled: in his own end.
There were many times when he was beaten by an opposing forward while pinching in the offensive zone too far, leading to an odd-man rush the other way. Dobson also typically got out-muscled in front of the Isles' net or even in the corners. Getting bigger physically should be a goal for him during this off-season. He almost acted like a lost forward while in his own zone, which is not something that the coaching staff was probably happy with on a nightly basis.
He certainly was not consistent enough either to be able to classify this season as a step forward for him. In January, Dobson only registered three points, all assists, and only scoring three goals in the last four months was not good enough to string more wins along for the blue and orange.
Fans of any New York team usually have less patience than smaller market teams' fans, and plenty called for Dobson to be traded after noticing his defensive liabilities during the past season. It would not be wise at all, however, to trade away one of the few cheaper young players that the Isles have whose role is to be a scorer (think back to Devon Toews) and getting rid of him before he reaches his full potential as an elite offensive defenseman would only make fans curse themselves years after.