Johnson, 22, was one of two Minor Leaguers sent from Los Angeles to Baltimore when the Dodgers acquired left-hander George Sherrill before the Trade Deadline. Dividing his season among three teams from Class A to Double-A, Johnson finished a combined 12-7 with a 3.41 ERA in 27 appearances, including 25 starts. He struck out 154 in 145 1/3 innings.
The Orioles then sent Snyder to the Rangers on Thursday to complete the deal for pitcher Kevin Millwood.
In the Draft's Triple-A portion, the Giants lost outfielder Brian Horwitz, a six-year member of the organization, to Cleveland.
"He's a good kid and a good hitter and he needs a change of scenery," Tidrow said.
Horwitz, 27, has a .316 batting average but only 22 home runs in 2,104 Minor League at-bats. The University of California graduate hit .222 with two homers and four RBIs in a brief promotion to San Francisco in 2008.Also in the Triple-A phase, the Giants plucked left-hander Jake Stevens from Baltimore's system. Stevens, 24, finished 5-6 with a 4.42 ERA in 34 relief outings for Class A Frederick last season. He's 37-42 with a 4.23 ERA in six professional seasons while dividing his duties between starting and relieving. The Dodgers raided the depths of the Giants' system to draft right-hander Raul Burgos in the Double-A portion. Burgos, 22, has never pitched above rookie-level ball in three professional seasons. He finished 2-0 with a 5.82 ERA in 15 relief appearances for the Giants' Arizona rookie-league club last season.
Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.