WASHINGTON -- The Nationals purchased the contract of right-hander Logan Kensing on Tuesday. This is his third stint with the team after being designated for assignment twice.

Kensing had a chance to become a free agent, but he never wanted to leave the organization because he likes the direction the Nationals are going into and they have given him an opportunity to pitch in the big leagues.

The Nationals, on the other hand, like his potential as a reliever. But Kensing hasn't been successful on a Major League mound this season, giving up 31 runs in 26 2/3 innings.

"We are continuing the evaluation process. We control him," general manager Mike Rizzo said. "We want to see if he is learning the things from Triple-A. He had a great season in Triple-A. We want to see if he can extend it to the big leagues. If he can, he is a guy we can think about in the future."

Kensing is a guy who will not give excuses on what went wrong on the mound. He simply said that he trying to find consistency.

"I was consistent until this year, when I had a couple of speed bumps," Kensing said. "I'm trying to work through those. I was real consistent in the Minor Leagues. As long as we can bring it up in the Major Leagues, I think we'll get through this year and finish solid. Next year, everything restarts for everybody and that will be kind of a relief to me. I've had a nightmare season so far."

Pitching matchup
WSH: RHP Garrett Mock (3-7, 5.63 ERA)
In his previous start, Mock had nothing in the tank, giving up six runs in his three frames against the Marlins. The long ball was the main culprit. In the first inning, Jorge Cantu took an 0-2 pitch and hit a two-run homer, while John Baker hit another two-run shot two innings later. Mock said he had mechanical issues on the mound. Most of his pitches were up in the strike zone.

PHI: LHP Cliff Lee (12-11, 3.06 ERA)
Lee has been bounced around in his past two starts, giving up 12 earned runs in only eight innings, both losses. Lee is coming off a three-inning effort at Houston in which he gave up six earned runs in a 7-0 loss to the Astros. It was quite a departure for Lee, who began his stint with the Phillies by winning five consecutive games. It will be the first career appearance against Washington for Lee.

Tidbits
Cristian Guzman has 48 multihit games this season. ... Willie Harris has two home runs in his past two games. He is hitting .230 with seven home runs and 23 RBIs. ... Ryan Zimmerman has struck out 100 times this season.

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Up next
• Thursday: Nationals (Livan Hernandez, 7-10, 5.44) vs. Phillies (Joe Blanton, 9-6, 3.80), 7:05 p.m. ET
• Friday: Nationals (J.D. Martin, 3-4, 4.35 ERA) at Marlins (Josh Johnson, 14-4, 3.04), 7:10 p.m. ET
• Saturday: Nationals (TBD) at Marlins (Anibal Sanchez, 2-6, 4.47), 6:10 p.m. ET