There's no need for them to place ads between rounds, 30-45 second ad slots won't be in danger of running over, and if they're going for full minute ad slots they'll probably run split-screen ads like you see during 30-second timeouts in NFL broadcasts.
There has, however, historically been a whole lot of completely dead air time and brutally awful commentary between fights, especially when early finishes happen. Replacing that with commercials doesn't inherently make anything about the broadcast worse, although they'll probably be running ICE recruitment commercials every break, which is another issue altogether from running commercials in general.
