I'll tell you a story. I saw Nigel do a presentation a couple of months ago, it was wide ranging but he talked about management styles and how he goes about things. As a player he had a lot of managers of course, and he talked about managers (can't remember who in particular) who would rant and rave at half time every week. Fifteen minutes later he walks back out onto the pitch thinking "so what are we going to do for the second half?". He talked through his normal half time routine, which is to take the first 2-3 minutes to check injuries, and then talk about what he wants to change. Last season away at Brighton, we had just gone 1-0 down (Jaidi error as I recall), he canned all that and stormed in, kicked the bin over and hairdryered away (to paraphrase), and we know how that one turned out.
So the point of all this is that while he definitely has a calm style, he can turn it on if he wants to. I suppose his only aim is to get the team to play better, and it's his job to work out the best way to do that.