I've had this issue since launch. If you're good at this game expect it to continously overrate your ability to carry a team.

I'm by no means the best, but I can regularly get top 3 in CQ with any class, although recently I've been playing purely infantry scout. If I have a really strong round, and my squad wasn't as high up, we are guaranteed to lose the following match. It happens almost every time. However, if your squad has several strong players then it's more likely to stay balanced.

Part of the issue is the fact that decent players obtain exceptional scores when given a good team. It's not uncommon to go something like 50-2 with scout if you have a good team. However, this doesn't mean you're some one man army as such. Give the same player a poor team and they probably will still get top score but with a much lower SPM/KD.

The team balancing doesn't account for this however and seems to value these players as being worth several men. It skews the skill distribution across the two teams to account for really strong top 3 players, but doesn't take into account the loss of performance of those top 3 players when not paired with a completely competent team. This causes a constant pendulum effect where essentially most matches are one side raping the other. You have rare servers where you can have a couple of equal games but people end up leaving and the skew happens again due to mostly random squad distribution.