Uh-oh. The latest news about Joe Mauer's back isn't good. From Aaron Gleeman:

After meeting with various doctors about his back injury, Joe Mauer admitted Friday that he's unlikely to be ready for Opening Day and general manager Bill Smith explained that "there's not a timetable right now to say when he is going to be on the field." Being without Mauer for a significant chunk of the year would be a massive blow to the Twins' playoff chances, but if he's able to return after sitting out weeks rather than months the team is relatively well-equipped to handle his absence. Mike Redmond will take over as the starter behind the plate, with either Jose Morales or Drew Butera (or perhaps both) serving as his backup. Redmond has hit .327/.382/.426 against left-handers over his career, including .350/.398/.439 from 2006-2008, so being without Mauer versus southpaws won't be a major downgrade for the Twins' lineup. Mauer posted flukishly big numbers versus lefties last year, but from 2006-2008 hit .329/.393/.432 against southpaws to nearly duplicate Redmond's career mark. However, replacing Mauer against right-handers is a much different story… --snip-- In other words, even if the Redmond-Morales platoon is utilized properly and both players perform well in their roles, being without Mauer would likely cost the Twins approximately one win every two months and 3-4 wins over the course of an entire season. Utilizing a Redmond-Morales platoon improperly by playing Redmond against most righties would increase the number of runs lost and pairing Redmond with Butera instead of Morales would magnify the dropoff even further. All of which is a long way of saying that being without Mauer for a few weeks would cost runs, but being without Mauer for a few months would cost wins. Redmond is among baseball's best backup catchers and Morales has hit well enough at Triple-A to suggest that he's a capable backup too, so the Twins are as well-equipped to weather the loss of an MVP-caliber backstop as could be expected. Still, Mauer is so much better than the average catcher that well-equipped or not his absence is a huge blow.

Well, yeah. Mauer is one of the five best players in the American League. I'm not saying Gleeman's math is off, but if you replace one of the best players in the league with Mike Redmond and Jose Morales or whomever, I have to think you will lose more than three or four wins. Maybe five or six. Which is too many, considering the Twins probably aren't a 90-win club even with Mauer playing 145 games. Of course, it's terribly early to suggest that Mauer will miss the whole season or even most of it. And there's nothing particularly special about the Twins; with the exception of perhaps the Red Sox, few contenders can easily shake off the loss of their best player.