Actually Yzerman always had a sense of humor. He was one of the biggest smartasses on the Wings, but he kept it pretty well out of the public. You didn't really hear stories until later in his career, and especially after he retired.
Though there is the infamous moment of him taunting Domi from the bench with the heavyweight belt gesture after Domi's rematch with Probert.
Toews just seems like he has zero personality.
At the 1:45 mark you see Stevie with the gesture...