Simple idea on how to fix the ranked pop issue....

[Nikoto]

exactly, they dont need to add extra stuff to ranked they just need to make it more attractive to those who wanna grind the series pass

I think they could consider adding an extra reward to rank placements, items like the GSP tokens that give funny Manderville coins. It'd essentially be based on placement how many you get, but it'll act as an EXP boost for the Series Malmstones. Players can decide to use it on the current series, or save it until the next one. Bronze gets 1, Silver gets 2, so on.