Diaz picked up the save Sunday against Milwaukee, striking out two during a perfect ninth inning.

Diaz needed only 14 pitches to retire Willy Adames, Garrett Mitchell and Joey Ortiz in order. The 27-year-old reliever has converted on 23 of his 25 save chances this season and has a 4.17 ERA with a 40:25 K:BB across 41 innings.

Lambert (thumb) allowed two hits and a walk while striking out three over 2.1 scoreless innings in Sunday's 9-8 win over Atlanta.

Lambert bruised his thumb in an appearance versus the Mets on Thursday, but he was able to return in short order. Sunday marked just his third scoreless outing in seven appearances since the All-Star break, as Lambert remains in a long-relief role. For the season, he has a 5.73 ERA, 1.55 WHIP and 47:24 K:B through 55 innings over 25 appearances (three starts).

Vodnik allowed a hit and struck out one over a scoreless inning to earn the save in Sunday's 9-8 win over Atlanta.

Vodnik erased a leadoff single with a double play and then struck out Travis d'Arnaud to make the Rockies' eighth-inning rally stand for the win. Vodnik has kept runs off the board in seven of his last eight outings, though the exception in that span was a three-run meltdown versus the Mets. He's now up to eight saves while posting a 3.92 ERA, 1.42 WHIP and 56:27 K:BB through 62 innings this season.

Walston (elbow) struck out five and allowed two hits and no walks over 3.2 innings in a rehab start for Triple-A Reno on Sunday.

According to Jesse Friedman of GoPHNX.com, manager Torey Lovullo said July 26 that the Diamondbacks were undecided on what Walston's role might look like upon the left-hander's return from the 15-day injured list, but Walston's usage Sunday implies that he'll be built back up as a starter. With Eduardo Rodriguez and Merrill Kelly both beating him back from the IL, the Diamondbacks don't have a rotation spot available for Walston at the moment, though the complexion of Arizona's pitching staff could change by the time Walston is ready for activation. Walston posted a 2.84 ERA and 11:9 K:BB across 12.2 innings in three outings (two starts) for Arizona before landing on the IL on June 6 with a left elbow strain.

The Cardinals activated O'Brien (forearm) from the 60-day injured list Sunday and optioned him to Triple-A Memphis.

O'Brien has been sidelined since he suffered a flexor strain Opening Day against the Dodgers, and he'll head to the minors now that he's healthy. The 29-year-old allowed two earned runs with a 5:4 K:BB over eight innings during his rehab assignment with Memphis.

The Phillies designated Nelson for assignment Sunday.

The right-hander has been at Triple-A Lehigh Valley since mid-April and has now lost his place on the 40-man roster. Nelson allowed two runs over 3.1 innings with the Phillies and posted an 8.35 ERA in 25 appearances at Triple-A.

The Diamondbacks designated Castellano for assignment Sunday, Alex Weiner of ArizonaSports.com reports.

The 26-year-old was optioned to Triple-A Reno on Thursday and has now lost his place on the 40-man roster. Castellanos posted a 5.23 ERA in seven outings for the Diamondbacks, and he could remain with Reno if he passes through waivers unclaimed.

Zastryzny (elbow) began a rehab assignment with Triple-A Nashville on Friday, striking out a batter while allowing two walks and one hit over a scoreless inning in his first appearance.

Zastryzny may require another appearance or two in the minors before the Brewers bring him back from the 15-day injured list. Before being deactivated July 26 due to left elbow tendinitis, Zastryzny made nine appearances for the Brewers and posted a 1.17 ERA, 0.65 WHIP and 5:1 K:BB across 7.2 innings.

Megill (back) is scheduled to throw a live batting practice session Monday, Sophia Minnaert of Bally Sports Wisconsin reports.

According to Adam McCalvy of MLB.com, Megill will head out on a rehab assignment if all goes well during Monday's throwing session. The right-hander was placed on the 15-day injured list July 29 due to a lower-back strain and likely won't need more than one or two tune-up outings in the minors before rejoining the Milwaukee bullpen. Megill leads the Brewers with 20 saves on the season, but he'll likely have to settle for setup work moving forward after closer Devin Williams returned July 28 from a season-long stay on the IL.

The Brewers transferred Paredes (forearm) from the 15-day injured list to the 60-day IL on Sunday.

The transaction clears room on the 40-man roster for southpaw DL Hall (knee), who was activated from the 60-day injured list ahead of his scheduled start Sunday versus the Reds. Paredes was initially placed on the IL on July 3 due to right forearm tendinitis and won't be eligible to rejoin the Milwaukee bullpen until early September.