How would you choose between Josh Willingham and Michael Cuddyer? They are the same age (born a month apart) and have accumulated the same amount of career fWAR. They both are a bit of a drag in the field and both are a bit lead-butted on the bases. Both are six feet and two inches tall. Both weigh within five pounds of each other. In fact, they could be the same exact guy if you didn't know any better.
If you look at the WarGraph below (thanks as always to Fangraphs), you see similar careers:
Willingham's WAR accumulation has been more consistent and smooth. Cuddyer was hurt in 2008 and then played considerable chunks of time (to disastrous fielding results) at first base in 2009 and 2010. Before 2008, it appeared that Cuddyer was the better player. But since 2008, Willingham has made up ground. Willingham has a slightly higher slugging and on base percentage while Cuddyer has a higher batting average.
All this observer is trying to say is that replacing Cuddyer with Willingham is pretty much a wash. You don't improve the overall Twins team if you look at it one way or you replace Cuddyer's production that would have been lost if you look at it another.
Harder to measure (or even talk about) are the intangibles. Cuddyer is a career Twin and therefore immersed in that culture. Willingham has been exposed to multiple cultures. Cuddyer is said to be a great clubhouse guy (whatever that means). Never heard those same kinds of comments about Willingham. Cuddyer has played on playoff teams. Willingham has mostly played for bad teams. Do you give Cuddyer an edge there?
When all is said and done, it seems that your view of what the Twins might do depends on if you are glass half full or half empty kind of person. Willingham replaces Cuddyer's production quite well. And yet replacing one for the other really doesn't improve your ball club. It just makes it similar.
There is one major difference so far unspoken. Willingham (to this point) has been much cheaper to employ than Cuddyer.