I tank 2 seasons, and play 2 seasons. Whit this method I won 5 Champions Leagues consecutive, and hope that this month and the next will win the 6th and 7th.
I obtained a 8* player doing that but with 3 months can be 9*.... (coz are 3 of tanking +1 to win the league in same level, so 4 months for a 9* or maybe 2)