In 2010, the nine members of the Twins' Opening Day lineup missed a total of 319 games. The reasons differed -- injury, performance, routine days off -- but that's an awfully large number of games missed by players that the Twins expected to be regular contributors at the outset of the season.

We can point to a variety of reasons for the Twins' success in a 94-win season, but one that stands out above all others is excellent depth across the board.

You could see it in the lineup. When Orlando Hudson and J.J. Hardy were nicked up, Alexi Casilla was there to step in with solid interim performance. When Nick Punto and Brendan Harris couldn't hack it at third, Danny Valencia took over with a tremendous rookie campaign. When Justin Morneau went down, Jim Thome became a lineup staple and picked up the slack.

You could see it in the pitching staff, too. When Nick Blackburn earned himself a demotion to Triple-A, Brian Duensing helped keep the rotation afloat with strong outing after strong outing. When Joe Nathan went down in spring training, Jon Rauch (and subsequently Matt Capps) filled his shoes, and the bullpen's overall depth enabled the team to sustain the loss of its closer with virtually no ill effect.

If there's one thing that troubles me in taking a preliminary glance at the 2011 roster, it's a disturbing lack of depth.

Should Casilla or Tsuyoshi Nishioka struggle or get hurt, the top backups right now are Matt Tolbert and Trevor Plouffe. Should Mauer miss extended time, the Twins will be regularly trotting out one of the worst hitters in the major leagues in Drew Butera. Should Morneau be unable to go, we're looking at another summer of Michael Cuddyer at first and Jason Kubel in right. Should a starting pitcher struggle or go down, the Twins would almost have to look to 23-year-old prospect Kyle Gibson, ready or not. Don't even get me started on the bullpen, where there isn't one player you can confidently call a major-league pitcher past Capps, Jose Mijares and a recovering Nathan.

I believe that the starting nine currently slated to take the field in 2011 can absolutely be playoff-caliber -- yes, even without Hardy. What I worry about is what happens if those projected starters miss another 300 games. Or even 200. While not impossible, it's a stretch to believe that someone like Tolbert or Plouffe or Jason Repko is going to be able to step in as a competent regular over a lengthy period of time should a starting player go down or slump badly. Similar things can be said about the rotation and bullpen.

Of course, the good news is that we're in mid-December and there's still plenty of time to address these depth concerns. What's not clear is how much funding is available to do so. Trading Hardy and Harris cleared about $7.5 million from the payroll, but that money will only go so far. For instance, it would only cover a portion of Carl Pavano's salary, and while that signing would shore up rotation depth it would leave a host of issues remaining to be addressed in the bullpen and around the field.

As of now, the Twins have right around $100 million committed to the 2010 payroll. That's about where they were this year, so it will be interesting to see how much higher they're willing to go in the quest to build depth.

At first base, will the Twins invest in a righty-swinging backup who can provide legitimate Morneau insurance while also protecting Kubel from southpaws at DH? (Paging Derrek Lee...)

What about the rest of the infield? With question marks all around the diamond, the Twins will likely yearn for a strong defensive backup who can cover any position. In other words, there's a high probability that Punto is re-signed. (Sorry gang.)

What about the bullpen? Bill Smith can play coy and act like he's comfortable with what he's got, but let's think about that for a minute. Last year he was so uncomfortable with a bullpen that included Rauch, Jesse Crain and Matt Guerrier (now all free agents) that he felt the need to trade away a top prospect and spend millions in adding both Capps and Brian Fuentes. Now he's pretending to be comfortable with Pat Neshek as a potential setup man? Right. My guess is that the Twins re-sign one of Crain and Guerrier and then wait until January or February to see what kind of bargains they can get on leftovers from a deep relief market. Not a bad strategy, all things considered.

In the rotation, it sounds as though the Twins have their sights set on Pavano, but one has to wonder whether they can afford to spend close to $10 million on him alone with so many other needs to address. Maybe they can backload his contract, or maybe they'll have to look elsewhere. It's hard to imagine they'd be comfortable going forward with only five proven starters, particularly with the performance issues of Blackburn and the injury issues of Scott Baker and Kevin Slowey.

Finally, what of Thome? Everyone would love to have him back, but if he wants $3-4 million, can the Twins afford to spend it on a guy who can't field a position and is somewhat redundant with players they already have? He's the definition of a luxury, which is a lot more palatable at $1.5 million than twice that much.

These are questions to keep in mind as the offseason progresses.