I might be wrong Usunfgames but is that happening because your not allowing for the percentage difference in the teams.
I'll explain....
If a 2 star team in the lower level draws or defeats a 4 star team that's a suprise because the 4 star team should be about 50% stronger if you looked at the qlty difference. When you at level 20 play a team 2 stars weaker the overall difference will only be about 10% stronger.
Or to put it another way if a 40 qlty team plays a 36 that's not a guaranteed win. At your level and i'm guessing if your team is 150 qlty and you play a 135 team neither is that. It's the same match but with the numbers bigger