FORT MYERS, Fla. - The Minnesota Twins have traded right-handed pitching prospect Billy Bullock to the Atlanta Braves, which allows them to retain Rule 5 draft choice Scott Diamond.

The Twins announced the deal on Monday. They plucked the left-handed Diamond out of the Braves' system in December. He allowed one earned run on six hits in six innings of work during spring training. But he missed two weeks with a blister on his left thumb and wasn't deemed ready for the opening day roster.

Because he will start the year at Triple-A Rochester, the Twins had to work out a deal with the Braves for Diamond or put him through waivers before they could retain him.

The Twins drafted Bullock in the second round in 2009. He struck out 60 batters in 36 2-3 innings at Double-A New Britain last year.