Normally win rate would be a great indicator. But now we are still in a transition phase where people try to figure out whether to proceed to the higher league or not. Many choose to proceed although they rather shouldn't. Eventually, more people will realize that playing in lower leagues will benefit them more, which will lead to greater competition in each league, leading to more losses for most people, including the top spots. Right now you are facing all those players who cannot proceed to next league and probably should be a league lower than yours anyways. Of course that makes it an easy win.

Give it another month and maybe some slight reward tweaks from the game and the situation will be very different. I trust that the devs are observing very closely what is going on to drive the ship ahead, as they have always done in the past years.