While I would not argue that Plouff is the overall better player, he is established at that position. It happens a fair amount that when a team has a player they want up now, they find a place for them if they are blocked at there native position. It does usually happen at least a few months before they get called up (roster management), but it's certainly a common enough practice. Like a few have pointed out it seems to me it's a four player juggle. If I were the manager, I'd prefer to see Sano get the majority of the starts at 3rd and playing right when Mauer doesn't with Plouff splitting time with Park at first. Just a thought.