I am pretty sure you're misremembering. Just like the NFL, each division rotated interleague, plus you always played your National League counterpart division. For the Twins, that meant every year they faced Bagwell, Biggio, Pujols, Sosa, McGwire, Braun, Fielder, Junior Griffey, and others each season along with a rotation that would come through depending on the division. When you can see Sammy Sosa at the height of his glory every season, it's not that big an event. When you only get to see Barry Bonds once every four years, folks come out for that, and they did heavily.