I don't know why, but the snapshot of my league team is affected by my season team. If I select a weak team with no gear for season, the next snapshot of my league team will have all gear removed.
I've moved these from Chit Chat to improve awareness about this bug.
There's a bit of a delay for stats to change accordingly, but this definitely happens (at least to a number of us).
@Tohru - Kinkoid @Luna - Kinkoid To summarize: it's not as simple as switching the teams as such, but having a weaker team selected in an entirely different part of the game (Season is confirmed, but I also suspect both Villains and Pantheon) currently reduces your League's team stats significantly.