You're talking about losing one game and being out versus losing three games and being out. Given how the 2000s Twins played in the playoffs, the difference is moot. For example, I wouldn't call the 2008 Twins and unsuccessful team. They had a successful season, they just got beat in a dramatic game. Baseball is unique because of the lack of teams that make the playoffs (roughly half of what makes it in the NBA and NHL) and the grinding, grueling schedule. Any time you survive 162 games - be it because of weak division opposition or not - and have a chance to win a pennant - then you've had a successful season. Whether your first series is best of one or best of three seems like an odd line to draw between success and non-success.