The Minnesota Twins had a busy spring, signing AL MVP and hometown hero Joe Mauer to an eight-year extension and holding auditions to fill the closer’s role after losing four-time All-Star Joe Nathan to Tommy John surgery. But the most significant offseason activity might have been the middle infield defensive upgrades.

Last season, the Twins lost approximately 33 runs as a team defensively, a total that placed them 28th out of 30 teams in Major League Baseball. The main problem was the keystone combination. Their second basemen lost an estimated 22 runs defensively in 2009 and their shortstops lost 24. The main culprits were Orlando Caberera, who cost an estimated 33 runs at shortstop for Oakland and Minnesota last year, Alexi Casilla (-12 Runs Saved at second base) and Brendan Harris (also -12 combining his play at shortstop and second base).

With a crowded outfield including Delmon Young, Denard Span, Jason Kubel, and Michael Cuddyer, the Twins traded center fielder Carlos Gomez to the Brewers for 27-year-old shortstop J.J. Hardy, who is coming off a disappointing 2009 season offensively. Hardy has totaled 20 Runs Saved over the last three years, and we project him for another 7 Runs Saved this year.

Orlando Hudson spent most of the winter without a home until the Twins stepped up with a one-year, $5 million contract. Hudson has totaled 18 Runs Saved over the past three years and also projects to 7 Runs Saved for 2010.

The loss of Carlos Gomez will cost the Twins defensively. He is among the best center fielders in the game. But the projected 31-run gain at shortstop and 29 runs gained at second base defensively will more than make up for it. Overall, we project the Twins to improve their defense by 39 runs over last year. Using the widely-accepted maxim that 10 runs is roughly equal to a win in the standings, the Twins’ are projected to improve by four wins on defense alone.

In addition to the defensive upgrade, the Twins will see better offense from their middle infielders as well. Last year, Twins shortstops and second basemen combined for 117 Runs Created, while we project Hudson and Hardy to create 158 runs with their offense. The offensive upgrade combined with the defensive improvement should make the pain of Nathan’s injury hurt a little less.