Sipp activated, Jennings designated, Guerra acquired

NEW YORK - As they prepare to open a four-game series against a reeling Mets club, the Nationals are remaking their bullpen on the fly again.

The Nats have activated left-hander Tony Sipp off the injured list while also claiming veteran right-hander Javy Guerra off outright waivers from the Blue Jays. Dan Jennings, an in-season acquisition who never found his footing, was designated for assignment to clear one roster spot. They'll need to clear another spot on the 25-man roster for Guerra once he joins the club.

Sipp spent the last two weeks on the IL with a strained right oblique muscle, but his rehab was brief. He made one appearance for Single-A Potomac, tossing a scoreless inning with one hit and two strikeouts. The 35-year-old had a 6.00 ERA in 17 appearances to begin the season but he hasn't allowed a run over his last nine outings.

Sipp's return made Jennings expendable, only five weeks after the Nationals signed the veteran lefty to a minor league deal and only three weeks after they added him to their big league bullpen. Jennings, though, struggled mightily in his short time with the club. He allowed 16 batters to reach base in only 4 2/3 innings spread out over eight appearances.

The Nationals will hope things work out better with Guerra, a veteran of nine major league seasons who had been pitching relatively well for the Blue Jays (3.84 ERA, 1.214 WHIP) in 14 appearances but was the victim of a bullpen roster crunch over the weekend and was designated for assignment to make room for lefty Ryan Feierabend.

Guerra, 33, has made 212 total appearances in the majors with the Dodgers, White Sox, Angels, Marlins and Blue Jays, compiling a 3.44 ERA and 1.408 WHIP.

The Nationals enter their four-game series with the Mets (who have lost five straight) with the majors' worst bullpen, a group that owns a collective 6.60 ERA.