Mock, 25, is slated to make his Major League debut with a start against the Giants on Sunday. Mock, who was acquired from the Diamondbacks in the Livan Hernandez trade in August 2006, is finally over his left knee injury. He is 3-2 with a 3.06 ERA in 11 starts. He has struck out 51 batters in 62 1/3 innings.
As for Mackowiak, he was slated to be a fourth outfielder this season, but the job went to Willie Harris. Mackowiak batted .132 with one home run and four RBIs in 38 games with the Nationals this season. He had signed with Washington for $1.5 million last December.
"When you hit .132, you can't expect to hang around. I didn't perform with the little appearances that I had," Mackowiak said. "I guess the only thing that bothers me is the when you decided to sign the team, you were promised more at-bats. I understand they have their guys they want to play. I didn't do well when I got in there. I had a horrible spring. It's my own fault. The team has to make a move, so they have to move on."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.