It's my ridiculously low average quality.

Now I'm level 33 with average team quality of 158.0
Since at level 33 a one star player is q160~164, my team is zero star average. It was even lower before the new version forced hundreds of skill points to be assigned.

The lowest quality player in my team is negative 4* at the moment, at 136q
And the highest is 181q at 5* which is the only player I bought this season.