Change the default setting for "auto renew enabled" from yes to no.
Change the default setting for "auto renew enabled" from yes to no in continuing leagues. I believe this contributes to the problem of inactive owners because it doesn't require owners to opt in to the league. I believe that by keeping the option available to auto renew but changing the default to no would help alleviate this problem.
Michael P. Dooley commented
I may start a new topic but rather than changing default would rather see that once players are opted-in at league renewal....the notice that goes out has a confirmation link thus Commish and other managers can determine which teams are in league via renewal event and of these which teams have confirmed or completed an opt-in to league. There are various permutations that could exist such as renewal and opt-in as it is now but if not accepted or confirmed after XX days or weeks, that team manager is removed and slot is opened up.
I find in numerous leagues that Commishes are trying to devise ways to confirm or separate inactive from active managers. e.g. in Keeper League with Keeper Tools enabled, league is renewed, manager can visit league, set keepers and yet their activity log for that league is no different for a manager that is still listed there via auto-renew and has never received or acknowledged that league has been renewed and their intent to return or leave league.