Just to add my 2 cents worth, I find that I get better results playing with a 'weaker' team.
Like the op I normally finish G3 or G2 in weekend league,(Ive only played one WL this season, so I'm talking about in general over the past few seasons) and I'm currently in D7.
As an example my cheap la Liga / ligue 1 hybrid is brilliant when used in rivals, Morales is a machine, use the same team in WL for two matches, and I got destroyed and when I used my strongest team in rivals it felt as if everything that could go wrong went wrong. Giving away pens, passes going completely astray etc.