See: First Base
See: Middle Infield
Third Base has been giving the Twins the gas face for most of their existence. Corey Koskie and Gary Gaetti were the only players that have been able to hold down the position for any length of time it seems. After a solid half season in 2010, Danny Valencia appeared to have a chance to do the same. In 2011, the average and on base percentage too massive hits. Valencia got less strikes and had more misses on swings than in 2010. In other words, he swings at bad pitches and pitchers know it. Also, his success against hitting the fastball in 2010 went by the wayside. Still, in his first full year Valencia is going to have an average in the neighborhood of .250 with 15 homers and 72 RBI. He plays a passable third base and does have some room for improvement; especially in the throwing department where the majority of his errors occurred.
I see Valencia holding down 3B again. Still a couple years away, but worth mentioning is Miguel Sano. He's 18 and already 6'3" and 230lbs and likely going to move from shortstop to third base as he develops. Here's what John Sickels says about him:
"Miguel Sano, 3B, Twins: Just 18 years old but hit .292/.352/.637 with 20 homers for Elizabethton, making a devastating one-two punch with Rosario in the lineup. Enormous power earned him $3.15 million in 2010. Superstar potential with the bat, but will have to watch strikeouts and sharpen up his defense."