Heed Brian's words of wisdom here. A team losing badly (even more so if it is an unexpected thrashing) are a potential red flag to the ref. The game can very quickly spiral into chaos, wild challenges, abuse (each other, opponents, spectators, anyone) and dissent is likely as the frustration levels increase.
There are several possible approaches, talking to them a lot more is both simple and effective. Talking all the time, so much so that they behave just to shut you up!
Or just wave lemons at everyone. Might make them behave a little better, but they will resent you for it. And if it doesn't work you have a full note book and a nagging sense that you perhaps could have handled things better after the game finishes.