Closing Time: Jason Grilli hurting, so we dial up Mark Melancon; Miami promotes two top prospects; Ziggy plays the ninth inning

Pittsburgh's bullpen has been a major factor in the team's renaissance season. The Pirates have a 2.77 ERA and 1.11 WHIP from their relief corps, outstanding numbers. But the man at the end of the bullpen, the man in charge of the handshakes, might be down for a while.

Jason Grilli was working on his 31st save Monday at Washington and was just two strikes away from completing the job before injury struck. Grilli was forced out of the game with what the Pirates are terming "right forearm discomfort." The club has a deep cast of characters ready to step into the gap if the All-Star closer is out for any length of time, but you don't lose a dominant force like Grilli (2.34 ERA, 0.92 WHIP, 13.4 K/9, 30-for-31 on saves) and not feel it.

Let's hear from the manager, Clint Hurdle. Here's what he told the team's official site.

"We'll wait and see where it all goes, but right now, it's right forearm discomfort," said Hurdle, cautioning reporters. "And that's all I've got, so no sense asking me anymore about it. We're not running him out of here. We'll see how he feels [Tuesday]."

Vin Mazzaro closed out Monday's win, but the logical saves hedge here is Mark Melancon. The well-traveled right-hander has rediscovered his game in Pittsburgh, posting a 0.97 ERA and 0.82 WHIP over 46.1 superb innings (six walks, 47 Ks). There's no reason he can't handle the ninth if needed, and he's still available in about two-thirds of Yahoo! leagues.

The Marlins have been the worst offensive club in the majors this year, with no one close. Miami has 309 runs scored on the ledger as we go to post Tuesday, 56 runs behind the No. 29 White Sox. You stream against these guys whenever you can.

[MLB Full Count: Watch live look-ins and highlights for free all season long]

Maybe an influx of youth will turn things around for the floundering fish. Miami's top two prospects, outfielders Christian Yelich and Jake Marisnick, were promoted from Double-A on Monday. Marisnick will probably get a chance to play center field right away, with Yelich settling into left. They're both widely available in Yahoo! leagues and worth immediate inspection.

The 21-year-old Yelich is considered the hitting jewel of the organization - he was a Top 15 prospect before the season. He's been good if ordinary in his Double-A work this year, posting a .280/.365/.518 line with nine homers and five steals (on 10 attempts) over 49 games.

Marisnick, 22, doesn't have quite the same pedigree - he's been in the 58-70 range on the prospect board - but he might be more ready for The Show. He compiled a classy .294/.358/.502 line over 67 games at Double-A, with 12 homers and 11 steals.

Marcell Ozuna and Justin Ruggiano are the fantasy losers in this exchange - Ozuna was optioned to Triple-A after Monday's game, and Ruggiano's .202 average will soon be on the bench full time. Ruggiano's in the middle of a strange fantasy year, providing some value (12 homers, 12 steals) despite the crummy slash line. All 12 of his homers have come in road games.

Houston prospect Jonathan Villar didn't arrive in the majors with buzz attached, but the new Astros shortstop has a chance to make an immediate roto impact. Villar batted .278 with eight homers and 31 steals at Triple-A prior to his recall, and he went 1-for-4 with a bag out of the leadoff spot Monday. You'll have to wait out the waiver process for Villar in most leagues, but maybe it's worth a stab. The Astros will give him every opportunity to prove himself, and they're apparently going to let him run right away.

If you need to know about Ziggy the guitar player, David Bowie is your man. If you're wondering about Ziggy the Arizona closer, talk to Kirk Gibson.

So tell us, Gibby - is Brad Ziegler your closer? Here's what the Diamondbacks official site has to say.

"It's somewhat by committee right now," Gibson said. "I kind of make my decision as it goes on within the game. Although I did tell Ziggy the other day that I was thinking he would be the guy, so that's kind of where I'm at right now."

The D-backs have a National League-worst 19 blown saves this year. Closer J.J. Putz missed time with an elbow injury and is still in the process of building up his arm strength. While he's doing that, the team has used him in non-save situations.

Setup man David Hernandez has had his share of struggles, but has pitched better of late. Heath Bell also got a chance at being the closer, but he struggled.

Ziegler said he was under the impression that he was the closer until further notice, but went out of his way to say that, while he enjoys the role, he doesn't see it as a long-term fit.

"I think, ideally, if everyone is pitching well then I'm not our closer," Ziegler said. "J.J. is the guy, or Heath is the guy or David is the guy. ... Their style of pitching is better suited for that role. I'm better suited to come in with runners on base. At the same time, when those guys are struggling if they feel I'm the best guy for that spot, then I'll jump in there and try and get three outs."

Ziegler has three saves in his last three appearances, working an inning each time. He's a pitch-to-contact guy all the way (4.8 K/9), but he keeps the ball in the park and has a ridiculous ground-ball bias (75.5 percent this year, 66.4 for his career). His HR/FB rate is actually a silly 18.2 percent for 2013, but that hardly matters given how infrequently batters lift the ball off him. Ziegler has also handled left-handed batters well this year, a problem area for him in the past. The submarine Snake awaits your call in 75 percent of Yahoo! leagues.

[Fantasy Baseball 2013: There's still time to join a league today!]

Speed Round: The Yankees and Cubs are working on a potential trade centered around Alfonso Soriano . . . Paul Konerko returned to action for the White Sox, going 1-for-3 with a strikeout . . . Bryce Harper is 5-for-20 with three walks since moving to the leadoff spot . . . Bronson Arroyo scattered seven hits in a Bay Area shutout, while Tim Lincecum was a flop (eight runs) in his no-hitter follow-up . . . Junior Lake collected four hits, including a homer, in Chicago's win at Arizona. He's been working as the team's center fielder and is off to a 9-for-17 start . . . A sore hip flexor knocked Miguel Cabrera out of Detroit's win at Chicago. He's considered day-to-day . . . Yu Darvish was sharp in his return to action, taking a shutout into the seventh inning against the Yankees. Ivan Nova took the loss but didn't fare poorly (7 IP, 7 H, 3 R, 3 BB, 4 K). Darvish works at Cleveland on the weekend, while Nova is home against Tampa Bay . . . Matt Kemp should be back later this week, as the X-rays on his ankle came back negative.

Related coverage on Yahoo! Sports:
Ryan Braun suspended for the season; who’s next?
Streaking Adam Jones, prospect talk and a look around MLB
Spin: Matt Garza to the Rangers for Mike Olt, CJ Edwards, others

What to Read Next