The Washington Nationals have designated veteran relief pitcher Brad Lidge for assignment, reports Danny Knobler of CBSSports.com. Ryan Mattheus has been activated as a corresponding move.

Lidge has struggled this season on the whole, but obviously fell quickly out of favor after back-to-back disasters against the Yankees. Friday night, Lidge gave up three earned runs in a third of an inning during a 7-2 Nats loss. Saturday afternoon, Lidge allowed the two decisive runs in the 14th inning, during a 5-3 loss in 14 innings.

"The 14-inning game forced us to make a move," Nationals general manager Mike Rizzo said (via Knobler). "Brad wasn't performing. He handled it like the professional he is. After last night, he kind of knew we'd have to make a move in the bullpen."

On the season, Lidge has a 9.64 ERA, 2.46 WHIP and one trip to the disabled list. He's walked 11 hitters while striking out 10 in 9 1/3 innings of work. Rizzo said that Lidge is completely healthy.

Mattheus, 28, has a 2.25 ERA, 1.30 WHIP and 13 strikeouts in 20 relief innings this season. He's been on the DL retroactive to May 21 with plantar fascitis.

If Lidge is not claimed off waivers or traded within the next 10 days, he could accept an assignment to the minors or become a free agent.

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