Is OP referring himself as the lightning or water main? Remember that root lasts only 2 rounds and the water main's 4th skill for the mystery can remove the root passive if that happened during your match.

It's rare but if you look at the water team OP suggested it could be that since you got the tag and maybe poison happening and the skewering would make sure the status effects be inflicted. If the water team weren't using that mystery then there would be no way for the water main to remove buffs or OP is just complaining how he lost in general and expected root to last for the entire match (which doesn't).