I disagree. A manager shouldn't be upbeat & positive all the time, it's a fake emotion.
Nigel is & as a result comes across, to me, as a little insincere, a little patronising, a little exaggerated & a little excessive. He regularly talks in a supercilious manner that I find irritating & fake.
I do think he's a nice chap, but if **** needs to be said then it needs saying, obviously in a constructive way. By masking over things with phrases like "control the controllables" & "we had a good warm up" he is basically treating his audience as idiots.