I love Splatoon, but the rank system is totally wonky, they dole out points based on the ranks of the teams playing, so if your S rank team faces another team of S rank squids, you'll never lose or gain more than 5 points, but if the other team has an S+ player and everyone else in the room is S, you'll gain 6 for winning and lose 4 for losing, but the inverse also applies; if the other team has an A rank player and everyone is S, you'll lose 7 points and gain like, 2.
It's frustrating since in lower ranks, you can go down as much as 16 points from one loss, but only gain 6 points from winning, meaning that if you break even, you're still playing at a deficit.
I'm fortunate enough to have made it to S, but since squads don't get you any points, I have to wrestle with the system, meaning Im gonna be S ranks for a lonnnnnnggg time.
Anyway, for losing streaks, its all about if you're having fun. I can lose but still keep playing since im still having a good time playing splatoon. If you're going down to the point where you're nearly deranked and cursng the world for your losses, you gotta ask yourself if you're having fun, and if not, stop.
It helps to wait for a rotation you're good at, I can't stand SZ so I do something else till RM comes on.