My Celtic is playing in league of 13x 5* teams. I've noticed some of teams were on same level last season. If they had wanted to gain some quallity advantage through tanking, they failed for sure. All teams have similar Q and after 3rd league round none of them has 3 wins. Now they can tank one season more 'cause league is very though, but that won't secure them 1st position next season. So I think that game creators found way to prevent tanking for stronger teams. For weaker teams (2-3* average quallity) it is still useful because they need time to get stronger, but for 5* teams it isn't anymore.