If you go to a concert, and the singer does not perform, the crowd are quiet. Just the same if a comic is telling all the old things you've heard before.
The crowd will cheer and encourage if there is something to cheer. It is so obvious, I can't believe this is even being talking about after today's – and other recent performances. Boston fans will get behind the team when they are playing well. Once more, particularly in the first half there was very limited action, especially goalmouth action . . . the crowd was quiet, in fact they were cold and stunned!