When trying to gauge the enthusiasm level of the crowd at a UFC event, I find it's helpful to measure the reaction by what I like to call "The Buffer Index."
It's not exactly scientific, but what it lacks in technical expertise it more than makes up for in pure simplicity.
It all boils down to how much of Bruce Buffer's pre-fight introductions you can actually hear over the noise of the crowd before the main event. If you can hear it all, that's zero Buffers. Every other word? Half a B