The Nationals activated Schultz (elbow) from the 15-day injured list Tuesday, Mark Zuckerman of NatsJournal.com reports.

Schultz missed much of spring training and the start of the season while recuperating from right elbow inflammation, but he's ready to go after making three rehab appearances. He was claimed off waivers by the Nationals over the offseason and is likely slated for a middle-relief role.

Perez (1-1) picked up the win Monday, allowing one hit in a scoreless ninth inning to close out a 9-6 victory over the Cardinals.

Despite pitching the ninth inning with a three-run lead, Perez was officially credited with a win and not a save as the Nationals' other relievers hadn't exactly been effective -- between them, Ken Waldichuk and Andre Granillo coughed up five runs in three innings. It's still intriguing high-leverage usage for Perez given the unsettled nature of the Washington bullpen, but the 29-year-old southpaw has only avoided allowing any runs himself in two of his five appearances to begin the season, stumbling to a 14.73 ERA and 3:2 K:BB in 3.2 innings.

Zastryzny (shoulder) was diagnosed with an intercostal strain and will be sidelined until at least late April, Todd Rosiak of the Milwaukee Journal Sentinel reports.

The 34-year-old lefty sustained the injury during his rehab assignment over the weekend while working his way back from a shoulder strain. Zastryzny will be sidelined for at least a couple more weeks as he contends with the new injury.

The Phillies activated Kerkering (hamstring) from the 15-day injured list Tuesday, Todd Zolecki of MLB.com reports.

Kerkering got a late start to the season after straining his right hamstring during spring training, but he's ready to roll after four rehab appearances. The 25-year-old will settle into a setup role for the Phillies, though he could be eased back into high-leverage situations following the layoff.

The Phillies optioned Backhus to Triple-A Lehigh Valley on Tuesday, Todd Zolecki of MLB.com reports.

He's clearing out to make room on the active roster for Orion Kerkering (hamstring), who is returning from a stint on the 15-day injured list. Backhus has yielded three runs with a 4:1 K:BB over three innings out of the Phillies' bullpen this season.

Duran earned a save against the Giants on Monday, allowing one hit in a scoreless inning.

Duran entered in the ninth frame tasked with protecting a two-run lead. He allowed a two-out double to Willy Adames but ended the game by getting Luis Arraez to ground out. Duran is a perfect 4-for-4 on save opportunities this season and has given up just one run while posting a 7:0 KBB through 5.2 innings spanning six appearances.

Pagan earned the save Monday against the Marlins, tossing a perfect ninth inning.

Entering the ninth inning with a two-run lead, Pagan needed just 13 pitches to secure the save, turning in a clean and efficient frame. The 34-year-old has now converted four of his five save opportunities this season, though his 7.11 ERA remains inflated from a rough outing against Pittsburgh last Wednesday. Since then, Pagan's bounced back well, allowing just one hit while striking out two in three appearances.

Junk (0-1) took the loss Monday against the Reds, allowing two runs on seven hits and one walk while striking out three over 7.1 innings.

Junk turned in a strong outing despite being tagged with the loss, keeping Cincinnati hitless into the fourth inning before allowing back-to-back hits that produced the game's first run. The right-hander settled in from there, working three more scoreless frames before Tyler Stephenson led off the eighth with a solo homer that accounted for the final damage. Monday's outing marked the longest of the 30-year-old's career across 38 appearances. While Junk admitted in a postgame interview that he didn't feel he had his best stuff, his ability to compete and navigate deep into the game was an encouraging sign moving forward into his next start, scheduled against Detroit.

Zerpa picked up the save Monday against Boston, giving up one run on two hits and no walks in the ninth inning.

With closer Trevor Megill and top setup man Abner Uribe both likely unavailable after working each of the past two days, it was Zerpa who drew the save opportunity and came away with his first career save. Things weren't easy though, as Willson Contreras homered and Wilyer Abreu singled to bring the potential tying run to the plate, but Zerpa got Trevor Story to ground out to end the game. The left-hander should see occasional high-leverage work, but Megill and Uribe are still the primary ninth-inning options in most situations.

Mejia earned a save against the Astros on Monday, walking one batter and striking out one over 1.2 hitless and scoreless innings.

Houston had already scored twice in the top of the eighth inning when Mejia entered with runners at second and third and only one out. The right-hander impressively put out the fire, getting a flyout and groundout around an intentional walk to prevent any additional runs from scoring. Mejia remained in the game for the ninth and worked a 1-2-3 inning to secure his first save of the campaign. Victor Vodnik, who successfully converted a save Sunday, had worked on consecutive days and was unavailable for the ninth inning Monday. Still, given Mejia's impressive escape act in the eighth, it wouldn't be surprising if he gets additional chances to close in a relatively unsettled Rockies bullpen.