Every league plays by the same rules
Ranked now draws from the same pool of rules for every league. Before, lower leagues could only ever see a smaller set of possible rules while higher leagues saw more, so the rules you practiced against were not the rules you would meet as you climbed. Now the pool is identical for everyone, and only your tier decides how many rules stack on a match, up to three. Ghost Ranked also rolls a little richer, two to three rules per match instead of the old lighter roll.