In terms of Wins Above Replacement, Hardy's 1.8 this year ranks fifth in the American League on the FanGraphs leaderboard. Hardy's done this in only 70 games, as he's missed time due to a bruised wrist. His bat his been about league average for AL shortstops, while much of his value is derived from what UZR/150 suggests is well above-average defense. Hardy has been strong in UZR every year of his career, not just the 580 innings in 2010.
However, I am guessing the Twins will not look closely at WAR when making the decision on whether to tender Hardy a 2011 contract in December. They'll first need to determine how much Hardy will seek or earn for next year, his final season before free agency. It's promising that Twins only needed to give Hardy a $450K raise coming off a disappointing 2009 season. They might be able to sign him for less than $6MM one last time. Hardy can't be too aggressive in his salary demands, as his agent Mike Seal surely knows that UZR numbers probably won't help his client in front of an arbitration panel and weak offensive counting stats would hurt him.
The Twins probably haven't decided yet whether Hardy is worth $6MM or so to them in 2011. They'll be considering alternatives. Trevor Plouffe is an internal option, though his work in a second Triple A stint doesn't stand out. Alexi Casilla will be around next year as well. The free agent market is weak, with Juan Uribe one of the better options the Twins can consider. The trade market could offer Stephen Drew, Jamey Carroll, Jack Wilson, or even a second round with Jason Bartlett.