I have a very strong idea that I am currently researching. I've centered on 2003 as being the best year to have mutual excellent seasons by Pittsburgh and Kansas City - both have enough already to enable them to each win their divisions given some improvements, and once they make it to the postseason, all that is needed is some luck.
The basic plan requires these general improvements for the Royals - more pitching and a good first baseman - I think I can find a decent free agent first baseman for cheap, and starters having fluke seasons can't be too hard to find, either.
The Pirates are tougher, but I've got some ideas. Basically, if I can rebuild them to be in contention throughout the season, they'll never trade away core players (Aramis Ramirez, Kenny Lofton, Brian Giles, Jeff Suppan).
They need a first baseman, at least part-time, and pitching - however, I think I've found a way to add the pitching easily: the Pirates, rather than the Expos, purchase RP Luis Ayala, and then trade RP Mike Lincoln to the Giants for SP Livan Hernandez (in reality, Hernandez had worn out his welcome in San Francisco when he attacked someone with a golf club; he was traded to the Expos for RP Jim Brower - Lincoln is an improvement on Brower, so I figure the Giants would go for that trade instead). They also keep Matt Herges instead of releasing him in the offseason. This gives the Pirates three good starters and three good relievers, while eliminating a bad reliever. I can also have them sign 2B Mark Loretta and maybe a couple more relievers (Steve Reed and Felix Heredia, maybe), and they'll perform much better. None of these moves are at all implausible, I think.