His demeanor at the piano was very businesslike. He did not hot-dog at the piano. He would occasionally glance at Eugene Ormandy on the podium to make sure they understood each other, but he let his fingers do the talking.
Understated, and CLASSY!
When I am fronting a band, I make little nods to the other band members, and make barely perceptible changes in dynamics...and if they are good, the get it!
It is a very sensitive and organic thing.