Eventually, Sean Doolittle will move on from the defending World Series champion Nationals. At some point, Edwin Díaz will exit the Mets’ ninth-inning picture. Closers have shelf lives -- some longer than others, of course, but none forever.

For that reason, teams are always looking ahead to who might be next. For some, it’s a hotshot prospect. For others, it’s a veteran already on the big league staff. Here’s a look at who could succeed the incumbent closer for all five National League East teams:

Braves: RHP Patrick Weigel
Weigel has been a starter most of his professional career, but he made a few relief appearances late last year at the Triple-A level and the Braves were planning to use him as a reliever this season. The 6-foot-6, 240-pound right-hander has regained the mid-90s velocity he possessed before undergoing Tommy John surgery in 2017 and, more importantly, he’s still generating impressive downward movement with the sinker.

Had Weigel not undergone surgery in 2017, he would have likely already become a key piece within Atlanta’s bullpen. In 10 appearances as a reliever last season, Weigel limited opponents to a .090 batting average and recorded 21 strikeouts over 19 innings. The 25-year-old could initially provide value as a multi-inning option, but he has the mental and physical tools to serve as a late-inning asset and potential closer.
-- Mark Bowman

Marlins: LHP Alex Vesia
The most career saves by a left-handed Marlins reliever is five by Adam Conley, who has never officially been a closer. Over time, Vesia might change that, potentially becoming the first primary lefty closer in franchise history.

A 17th-round Draft pick from Cal State East Bay in 2018, Vesia has put himself in position to be part of the Marlins’ bullpen in '20, whenever the season starts. Spanning four Minor League levels, Vesia has an active string of 41 1/3 straight innings without allowing a run, dating to last July 13 at Class A Advanced Jupiter.

Ranked by MLB Pipeline as the Marlins’ No. 27 prospect, Vesia kept his scoreless streak going in big league Spring Training, logging six shutout frames in Grapefruit League games. That’s in addition to nine straight scoreless innings at Jupiter, 16 1/3 at Double-A Jacksonville and 10 1/3 in the Arizona Fall League. If he keeps putting up zeroes, Vesia, 23, could find himself working the ninth. -- Joe Frisaro

Mets: RHP Ryley Gilliam
The Mets have Díaz under team control for three more seasons, and if things break the way they hope, he’ll be the closer throughout his tenure in Queens. Even if Díaz continues struggling in the short term, the Mets have plenty of options to take over for him, from Seth Lugo to Dellin Betances to Jeurys Familia and others.

Longer term, the situation becomes more fluid. One name to note is Gilliam, a hard thrower whose ninth-inning work at Clemson enticed the Mets to draft him in the fifth round in 2018. The Mets' No. 27 prospect has since climbed all the way up to Triple-A Syracuse, struggling a bit at the upper levels last year but dominating in the Arizona Fall League. In his two-year Minor League career, Gilliam has struck out an average of 14 batters per nine innings. This spring, Gilliam earned his first invitation to big league camp, appearing in four games. He could be a bullpen option for the Mets late this season, and if he finds success at the highest level, a closing option for years to come. -- Anthony DiComo

Nationals: RHP Will Harris
With Doolittle in the final year of his contract, the Nationals' bullpen could look different after 2020. If so, the team recently added an experienced arm who could step into that role, inking Harris to a three-year, $24 million deal in January to enhance the back end of its bullpen. The 35-year-old righty has a 2.84 career ERA with 20 saves and 92 games finished over eight seasons. In '19 as a member of the Astros, Harris’ 1.50 ERA paced American League relievers. He comes to the Nats with a .987 WHIP over the past five seasons with Houston. As Washington looks to defend its World Series title and contend beyond that, Harris has appeared in 23 games (17 2/3 innings, 4.08 ERA) over four postseasons. -- Jessica Camerato

Phillies: RHP Connor Brogdon
The Phillies have a host of hard-throwing Minor League pitching prospects that could close one day, but Brogdon’s numbers really jump off the screen. Brogdon, 25, has a dominant fastball-changeup mix, throwing from a high three-quarter arm slot. His fastball touches 97 mph. His two-seam circle changeup is highly regarded. (Brogdon taught the pitch to right-hander Nick Pivetta, who is counting on the changeup to keep him in the rotation.) Brogdon struck out 106 and walked 24 in 76 combined innings last season with Class A Advanced Clearwater, Double-A Reading and Triple-A Lehigh Valley. He allowed only 46 hits. A 10th-round Draft pick in 2017, Brogdon missed a September callup, but he seems like a strong bet to make his big league debut sometime in '20, assuming play resumes. -- Todd Zolecki