Past series wins don't give you bonus points in future playoffs. It can be an indication of a team's quality, but there are significant limitations to what information a simple "did you win your series or no" answer can provide, as there are so many external impacting factors, and teams change so much from year to year anyway. Better measures of team quality or even why and how you won (or lost) and the context behind the playoff series and how the team performed would provide more information towards future cup potential than just the basic yes or no of did you end up winning that series in the past. You'd be surprised how many cup winning seasons are surrounded by disappointing playoff outcomes.