Need an impact arm or bat that can give your fantasy team a boost? Whether you're looking for an injury replacement or someone to stash on your bench, the fantasy waiver wire has a plug or long-term fix to pick up today. Check out the following 10 players -- all sitting on waivers in many leagues, and all ready to help your team in Yahoo Sports Fantasy Baseball, the Official Commissioner Game of MLB. All statistics and ownership percentages are as of Wednesday.
Ken Giles, reliever, Blue Jays (57% owned)
Giles is expected to slide into the closer's role with Toronto after being traded from the Astros, where he had a 4.99 ERA despite a 10.3 K/BB ratio and a 2.28 FIP. His .366 BABIP and 60.8 percent strand rate suggest he was extremely unlucky, so Giles should see better results with his new team. While his time in Houston ended poorly with a demotion to the Minor Leagues, he could benefit from a fresh start with the Blue Jays.
Sergio Romo, reliever/starter, Rays (55% owned)
Romo is still available in nearly half of leagues despite flourishing as Tampa Bay's closer. In addition to his 12 saves, he has a solid 3.61 ERA with a 1.25 WHIP and a 9.7 K/9 rate. While he lacks the elite ratios and strikeout numbers of the game's top closers, he's a quality late-game option worth owning in most formats.
Evan Longoria, third baseman, Giants (43% owned)
Longoria was dropped in a lot of leagues during his lengthy stay on the disabled list, but he's back after missing six weeks with a broken bone in his left hand. The long layoff doesn't appear to be hampering his swing, however, as he's batted .292/.357/.417 in his first six games back from the DL.
Carlos Rodon, starter, White Sox (41% owned)
Rodon's talent has often been limited by injuries throughout his career, but he's finally healthy again after opening the season on the 60-day DL with a shoulder injury. The 25-year-old southpaw has pitched well since returning, going 3-3 with a 3.24 ERA and a 1.06 WHIP while averaging 6.5 innings per start. He was even better in July, compiling a 1.88 ERA and an 8.5 K/9 ratio over four starts last month. If he keeps it up, the young lefty could be primed for a big second half.

Pedro Strop, reliever, Cubs (40% owned)
Strop has become Joe Maddon's first option in the ninth inning since Brandon Morrow (right biceps inflammation) went on the DL. Strop has picked up three saves since the All-Star break and should continue seeing opportunities for the foreseeable future, as Morrow has yet to resume throwing based on a July 29 update. With a 2.51 ERA, a 1.09 WHIP and an 8.6 K/9 rate, Strop should be a solid fill-in until Morrow returns.
Brandon Nimmo, outfielder, Mets (29% owned)
Nimmo has been one of the few bright spots for New York this year, slashing .252/.380/.473 with 13 homers and seven steals in his first full season. The 25-year-old has been the Mets' primary leadoff man this year and should continue seeing regular playing time with Yoenis Cespedes (heels) officially done for the year. His combination of power, speed, and counting stats makes him a worthy pickup in most formats, especially leagues that utilize on-base percentage instead of batting average.
Wily Peralta, reliever/starter, Royals (20% owned)
Peralta has emerged as Kansas City's primary closer in the second half with four saves in four chances since the All-Star break. He's made a smooth transition to the bullpen in his first season with the Royals after struggling in his last few seasons as a starter, notching a 3.14 ERA and a career-high 8.8 K/9 rate this year.
Jose Leclerc, reliever, Rangers (19% owned)
As the team leader in holds (15), Leclerc looks primed to take over the ninth-inning job in Texas following the trade of Keone Kela to the Pirates. The 24-year-old has been excellent this season, posting personal bests in WHIP (1.01) and strikeout rate (12.7 K/9) alongside a 2.27 ERA. He's greatly improved his control as well, yielding just one home run in 39 2/3 innings this year while nearly cutting his walk rate (4.3 BB/9) in half from last year (7.9 BB/9).

Anthony Swarzak, reliever, Mets (16% owned)
While it initially appeared that Robert Gsellman would inherit the closer role following the trade of Jeurys Familia, Swarzak appears to be the main option now after converting New York's last two save opportunities. Swarzak's career-high 10.8 K/9 rate makes him better suited for the role than Gsellman, who's more valuable as a multi-inning reliever and a spot starter. Although Swarzak has struggled this year with a 6.30 ERA and a 1.70 WHIP, his numbers are still stabilizing, as he's been limited to 20 innings by a strained oblique.
Mychal Givens, reliever, Orioles (8% owned)
Following the trades of Zach Britton and Brad Brach, and with Darren O'Day out for the season, Givens appears to be Baltimore's top closing option despite having only one career save to his name. Although his 4.78 ERA and 1.44 WHIP are lackluster, he's gotten unlucky with a .352 BABIP and a 63 percent strand rate. His 2.99 FIP suggests his ERA should be closer to his career 3.20 mark, making him an intriguing buy-low candidate.