Reg teams do exponentially better than random pub teams. This is because most of us know what the rest of us are good at. I always gorge, Bill always relocates, Scoot/HD/others are the bladed messiah, Asal is death on wings.
This means on such a team, you can have a reasonable guess as to where we are lacking. If I see regs on an alien team, then I know my job is gorge to back them up with a hive and chambers. If I see a stack of faces on Marines (Sheen, Scoot, Bill) then I can be fairly certain that a coordinated pack of rines is going to come barrelling towards the hive within the first 5 minutes.
If, on looking at the teams, the GAME (game, not match) is going to be a foregone conclusion, consider switching. Yes its dull when noone else will do anything constructive, and its freaking irritating when noone will ever consider defending the hive or placing rts, but at the same time its a bit of a challenge, as opposed to "lets see if I can beat my personal best".