I think by 2006 and probably earlier, you can't simply add Prior to the Twins real-life playoff results and conclude he wouldn't have helped. The composition of the team would have likely been quite different, for better or worse. Rick Reed and Mark Redman (plus Matt Lawton) could have been affected within two months, not to mention the Joe Mays contract extension, Kenny Rogers in 2003, the Eric Milton trade which netted us Silva and Punto, and certainly the AJ trade which netted us Liriano and Nathan (and Boof). And those are just the players and moves directly affected by Prior -- more certainly would have been affected indirectly. For example, maybe without Nathan, we hang on to Guardado or Hawkins a few more years? If you can look ahead a little further, maybe without Liriano, we aren't so eager to trade Matt Garza (or even Johan Santana) after 2007? Really, 2002-2004 are probably the only years where we can safely make guesses. And in 2002, swapping Mays or Reed for Prior likely wins us the ALDS in one fewer game, and if it was Reed who was out, perhaps extends the ALCS back to the Metrodome for Game 6... In 2003, Prior takes the Game 1 assignment from Santana and pushes Lohse out of the playoff rotation, and perhaps delays Santana's injury that October? Or at least allows him more time to recover. Similarly, with Prior in 2004, pushing Silva out of the playoff rotation and letting Santana work on full rest could change things quite a bit too. While SP wasn't always our top weakness those years/series, we certainly could have benefitted with another top level starter! (Who wouldn't?) I wouldn't, however, posit that Prior would have stayed significantly more healthy with the Twins. The frequency and severity of his injuries almost certainly would not have been avoided with a few lower pitch count games. Not a knock on Mauer at all, but it certainly would have been interesting to see Prior on the 2001-2004 teams. Perhaps even more interesting would have been the 2001 signal that the Twins were willing to spend some money to be the best. Maybe they go over-slot for future draft picks, or pony up for FA Jim Thome or international amateurs, etc. Maybe they even avoid the contraction mess, hire Molitor to manage instead of Gardy, get their new stadium a couple years earlier, etc. Lots of implications! Of course, in this bizarro universe, there is almost certainly a 2015 article asking "What if the Twins drafted Mauer instead of Prior?" Which likely concludes that the 2005-2014 teams would have been better off had they done so.