What a difference a week makes.

A few days ago I was thinking of writing a post praising the Minnesota Twins for being aggressive and filling nearly every hole in the team’s lineup heading into year one at Target Field.

I never quite got around to that post. And Tuesday morning the Twins’ fortunes took a dramatic turn for the worse when the Minneapolis Star Tribune reported that closer Joe Nathan is likely out for the year with a torn ulnar collateral ligament in his elbow.

In addition to the new ballpark, the offseason acquisitions of Orlando Hudson, Jim Thome, JJ Hardy and the Winter League performance of Francisco Liriano had enthusiasm higher than I ever recall it heading into Spring Training. The mood on Minneapolis sports talk radio  is decidedly more sanguine this morning. The Nathan injury is huge. He had some struggles at the end of the 2009 season but his numbers still put him well among the league’s elite closers.

Inside the organization the Twins did some work to solidify the bullpen late last season and during the offseason. Guys like Jon Rauch (from Arizona) and Clay Condrey (from Philadelphia) join holdovers Matt Guerrier, Jesse Crain, Jose Mijares, and Pat Neshek, who is returning from arm problems of his own, give the team the deepest mid-innings relief corps it’s had in years.

But as a closer Rauch has been middling at best. Guerrier has done a great job as a setup man for most of the past few seasons but his stuff doesn’t lend itself to closing. Crain, well, I almost forgot to include him on this list, if that says anything. And Neshek has long been talked about as Nathan’s heir apparent, but he hasn’t thrown an inning that mattered since May 8, 2008.

On the farm the Twins have Anthony Slama and Rob Delaney, but by most accounts they’re not ready to pitch in the Major Leagues, much less close. And does a team heading into the season with aspirations of making a deep run into the playoffs want a rookie in that role anyway?

One caller to KFAN’s mid-morning show mentioned the possibility of signing John Smoltz. He is available, though Yahoo! Sports just this morning published a report indicating that he and Pedro Martinez are both likely to sign mid-season deals with National League teams to continue their careers.

There’s also some talk about the possibility of putting Francisco Liriano in the closer role if Brian Duensing or Glen Perkins can fill the fifth starter spot. I guess it’s an option. But if Liriano is really pitching as well as the winter reports indicate he stands the best chance the Twins have of putting a true ace on the mound every fifth day. I would rather see him head the rotation than close.

There will probably be some guys that come available as teams fall out of the pennant race toward mid-season deadlines. But finding closers is difficult and they don’t come on the market very often. And there isn’t a team out there that is going to trade someone to Minnesota just out of sympathy. If anything the price in prospects probably just went up dramatically.

So, out of the gate, my best guess is that Mijares, Neshek and Guerrier start the season pitching the 7th and 8th innings in a setup role with Rauch becoming the closer. And if the team is doing well – as it still should – I’m guessing they’ll take a look at his performance and the available market and see if they are willing to swallow hard and cough up what it would take to bring in a top-notch closer with a bit more experience in the role.

But this is one of the toughest breaks this team has suffered in a long time.