There is a difference between being happy with a season's ultimate outcome and attempting to win the SuperBowl. Only one playoff team ends season with a win. Its silly to say a season with a division title and a playoff win is not a success.
However the offseason and in-season approach should have been win at all costs this year and next. Same approach LA is taking. Allen's contract along with others will soon make it difficult to compete. Look at what has happened to Seattle. The secondary got expensive and old real quick. The most expensive player on Bills D will be coming off an ACL tear. Edmunds and Oliver are going to want to be paid top dollar too. Beane will need to hit on multiple draft picks or find bargain basement free agents. He did exceptionally well with Brown this year, Rousseau looks solid, and Basham is finally playing.
Beane will have some room to maneuver with some high priced vets coming off the payroll. If the Bills don't win it all, then I would like to see Beane target 1-2 key free agents, bring back Wallace, trade out of the first round and get an extra day 2 pick, hopefully see Frazier sign with another team netting them two 3rd rounders, and then start packaging the low round picks for higher picks. 6th and 7th round guys aren't making this roster anytime soon and any street UDFA would be just as good. Trade those picks away to move up in the middle rounds to get the specific guys you need to plug the holes and stock the cupboard for next year or two.