The Twins have outrighted starter Nick Blackburn and infielder Tsuyoshi Nishioka off the 40-man roster, the club announced Monday.

Blackburn will be sent to Triple-A Rochester; Nishioka will remain on the Rochester roster.

After two solid seasons in 2008 and 2009 -- a 4.04 ERA, better than the league average by about seven percent -- Blackburn's once-pristine control betrayed him. He posted walk rates under 2.0 per nine innings in prior to the 2010 season but saw those rates balloon to 2.24, 3.28 and 2.37 the next three seasons respectively.

This year, Blackburn has allowed 23 home runs in 19 starts and owns an atrocious 7.39 ERA and 6.09 FIP.

Nishioka had a horribly disappointing season in terms of performance (48 OPS+) and injuries (just 68 games played) in his debut season last year. This season, he hasn't even hit in the minors -- .252/.311/.313 in 89 games for Rochester -- and has played just three games for the Twins.

He is under contract for 2013 at $3 million, with a $250,000 buyout on a $4 million option for 2014.

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