It's more like:
Alpha: Randos, people with no squad preference and people who are very new. Maintains good squad cohesion until first contact with the enemy, at which point 40% of them charge after it and the other 60% drop their guns in fear and flee. Actual effectiveness is completely random on a round to round basis.
Bravo: Fobbits. Get assigned to FOB duty 90% of the time. Utterly incapable of doing anything else. Even the simplest of non-FOB duties will confuse them and lead to them getting squadwiped immediately. The least effective squad when doing anything other than FOB, but usually contains at least one engineer who knows how to setup the FOB properly.
Charlie: Formerly RP Squad, currently suffering from Delta Contamination. Result is a mix and match of people with 20 different emotes macro'd and people who have 20 different weapon pickups macro'd. This dynamic actually makes them surprisingly effective, since there are enough ungas to fight effectively and enough wet blankets to maintain some level of squad cohesion and vaguely guide the ungas towards following orders.
Delta: Unga squad, live only to fight. The fact that this is now widely understood as part of the metagame means that they've attracted most of the players who play this like a pure team deathmatch. Individually more skilled than any other squad, but lose cohesion fast unless the squad leader is very good. Generally either smashes the enemy quickly or is completely wiped out within 20 minutes.