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Andy's FAAB fantasy baseball waiver wire pickups and bidding guide for Week 21 (August 18 - August 24). His recommended FAAB dollars to spend on waiver wire adds.
Happy Saturday, RotoBallers! With another week of MLB action in the books, it's time to place some more FAAB bids. If you missed out on one of the "new" closers following the wild trade deadline, don't fret, because we have a potential league-winner available in 60% of leagues. On the hitting side, we saw the Cubs promote their hitting prospect in hopes of breaking out of their August slump.
Our series about FAAB fantasy baseball waiver wire pickups continues as we head into Week 21 of the 2025 MLB season -- August 18 through August 24. This waiver wire article will recommend free agents to target and how much FAAB you should allocate for them.
Each week, I will break down at least one player from each position with ownership percentages under 40 percent in Yahoo! leagues who could improve your roster and provide you with an added boost in several categories. Be sure to follow RotoBaller MLB and me on X for all your fantasy baseball needs this season. Let's get to it!
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Fantasy Baseball Waiver Wire Hitters to Target
Adrian Del Castillo, C, Arizona Diamondbacks
5% rostered
FAAB Bid: <10% if needing a catcher, <1% for others
After showing flashes of upside during his debut season in 2024, Del Castillo has a rough start to 2025 after battling injuries in the first half. However, with Gabriel Moreno (finger) still on the 60-day IL, Del Castillo has full control behind the dish in Arizona.
Over his last five games, he has been deployed as a full-time starter and has been very impressive, posting a .316/.381/.632 line with three doubles and one home run. Given that he holds a career .296/.3854/.542 line at Triple-A, Del Castillo is an intriguing target if you need another backstop.
Francisco Alvarez, C, New York Mets
20% rostered
FAAB Bid: <12% if needing a No. 2 catcher, <2% for others
The 23-year-old had a rough start to the season, which eventually resulted in his demotion to Triple-A. Since returning to Queens, the former No. 1-ranked prospect in baseball has begun to look like his former self. Through his past 17 games, Alvarez has held a .280/.390/.580 line with four doubles, three home runs, and nnie RBI.
Hius 26.4% K rate is tough to swallow in points leagues, but if you need a boost of power at your catcher position, you won't find anyone with the upside as Alvarez.
Other C to consider: Dillon Dingler DET, Drake Baldwin ATL
Kyle Manzardo, 1B, Cleveland Guardians
15% rostered
FAAB Bid: <13% if needing power, <5% for others
Since July 26 (15 games), Manzardo has been one of the best hitters in baseball. During this stretch, the 25-year-old has posted an elite .354/.456/.708 line with five home runs and 11 RBI.
Manzardo appears to be finding his footing once again following a rough skid in May and June. He is a top target for power this weekend.
C.J. Kayfus, 1B/OF, Cleveland Guardians
10% rostered
FAAB Bid: <7%
My other first baseman also plays in Cleveland. However, Kayfus has been spending most of his time in the right field while Manzardo and Carlos Santana share time at first base. Since earning the call to the majors, Kayfus has looked very impressive. Over his last nine games, the former third-round pick has posted a strong .296/.345/.519 line.
He spent most of the season with Triple-A, where he hit 13 home runs and swiped two bags while holding a .283 AVG. Given his ability to play both first base and right field, he should continue to see everyday at-bats in Cleveland.
Other 1B to consider: Tyler Locklear ARI, Spencer Horwitz PIT
Blaze Alexander, 2B/3B/SS, Arizona Diamondbacks
15% rostered
FAAB Bid: <8%
Alexander has been one of the hottest hitters in baseball this month. Since August 1, Alexander has posted a .341/.460/.683 line with two doubles and four home runs. During this stretch, he has scored eight runs and tallied nine RBI.
While he holds a career .253/.336/.385 line through 292 career PAs in the desert, his 91.5 mph average exit velocity this season augments that he is taking a step forward. He has also generated an eye-ctaching 14.5% barrel rate and a 46.4% hard-hit rate.
Blaze Alexander in August:
.350 / 4 HR / 9 RBI / 1.158 OPS
13 K : 5 BBScorching hot this month!
pic.twitter.com/yHSsRr5Blq— Andrew DeCeglie (@Andrew_FBB) August 13, 2025
Other 2Bs to consider: Spencer Horwitz PIT, Otto Lopez MIA
Miguel Andujar, 3B/OF, Cincinnati Reds
8% rostered
FAAB Bid: <10%
The 30-year-old has been on an impressive run since joining the Reds. Through his first 10 games in Cincinnati, Andujar has posted a .370/.469/.778 line with a hefty 1.247 OPS. During this stretch, Andujar has launched three home runs and added two doubles.
Overall, Andujar has been very productive but has seen his productivity limited by injuries. Through 70 games, he is on pace to enjoy a career year, holding an .819 OPS with a .306 AVG and nine home runs. While playing could eventually be tough to see in a crowded Reds lineup, for now, he appears to be the everyday DH and has recently been bumped up to the cleanup spot.
Kyle Karros, 3B, Colorado Rockies
5% rostered
FAAB Bid: <4%
The Colorado prospect was a quiet promotion last week, but has been rather productive over his first week. Through six games in the majors, Karros has posted a .333 AVG with a 4:3 K:BB. He has scored five runs and tallied three RBI.
With Ryan McMahon out of town, Karros should continue to see everyday opportunities at the hot corner. He has also posted a strong batting average in the minor leagues and could find some untapped power upside playing at Coors Field.
Other 3B to consider: Joey Ortiz MIL, Blaze Alexander ARI, Noelvi Marte CIN
Joey Ortiz, 3B/SS, Milwaukee Brewers
10% rostered
FAAB Bid: <6%
The Brewers haven't stopped hitting, and neither has Joey Ortiz. Since July 30, the multi-positional infielder has held a .396/.442/.542 line. During this 13-game stretch, Ortiz has crossed home plate 12 times, tallied 11 RBI, and swiped two bags.
While he is not a target for power, he should continue to rack up counting stats playing in the hottest lineup in the sport.
Other SS to consider: Blaze Alexander ARI, Otto Lopez MIA
Owen Caissie, OF, Chicago Cubs
15% rostered
FAAB Bid: <8% in five-outfielder leagues, <4% for others
One of the two big prospect promotions this week was the Cubs' top outfield prospect. After being viewed as a top trade target at the deadline, the Cubs opted to hold on to their top prospect as he is now looking to kickstart a slumping offense. Although opportunities will be scarce, playing alongside Kyle Tucker, Ian Happ, Seiya Suzuki, and Pete Crow-Armstrong, he excelled as an elite hitter at Triple-A.
Through 93 games with the Iowa Cubs this season, Caissie held a .289/.389/.566 line. He is worth a speculative pickup in the deeper leagues, but do not blow your FAAB here.
Blake Perkins, OF, Milwaukee Brewers
5% rostered
FAAB Bid: <9% in five-outfielder leagues, <5% for others
Perkins made my column last week, and like Ortiz, he has the benefit of playing for the red-hot Milwaukee team. Over his last 12 games, Perkins has posted a strong .286/.352/.531 line with three home runs, six RBI, 14 runs, and three stolen bases.
While he could be held out of action against southpaws, given his ability to hit power and steal bases, he is a top target if needed as a strong depth outfielder in category leagues.
Noelvi Marte, 3B/OF, Cincinnati Reds
22% rostered
FAAB Bid: <20%
My final outfielder to target is creeping up on the 40% share mark and won't be available much longer, so act quickly! Since returning in early July, Marte has been one of the most consistent hitters in the game. Over his last 31 games, Marte has held a .300/.325/.518 slash line with nine doubles, five home runs, and three stolen bases.
His above-average .269 xBA, 74.2 mph average speed, and 90th percentile sprint suggest he should continue to possess five-actehrouy upside in the second half.
LITTLE LEAGUE HOME RUN FOR NOELVI MARTE! pic.twitter.com/aybzINWcZi
— Jomboy Media (@JomboyMedia) August 13, 2025
Other OFs to consider: Miguel Andujar CIN, Daulton Varsho TOR, Nathan Lukes TOR
Fantasy Baseball Waiver Wire Pitchers to Target
Nolan McLean, SP, New York Mets
20% rostered
FAAB Bid: <13%
The other substantial prospect promotion was McLean of the New York Mets. The No. 64-ranked prospect in baseball according to MLB.com is slated to join the Mets on Saturday afternoon to make his MLB debut against the Seattle Mariners. In a corresponding move, veteran right-hander Frankie Montas will shift to the bullpen.
At Triple-A this season, McLean has looked very impressive, holding a 2.78 ERA, 1.10 WIHP, and a 97:38 through 87 1/3 innings. He should be in a good position to hold this spot with Montas now moving to a relief role.
Jacob Lopez, SP, Athletics
35% rostered
FAAB Bid: <28%
The Athletics southpaw was the feature of the multiple columns last weekend, and he has yet to slow down. This week, Lopez tossed seven shutout innings with only four hits and 10 punchouts against the Tampa Bay Rays.
Since July 26 (four starts), Lopez has posted a perfect 0.00 ERA with a 0.83 WHIP and a 28:6 K:BB over his last 24 innings. He is a must-add in all leagues.
Jacob Lopez last 4 starts:
24 IP
28 K
0.00 ERA
0.83 WHIPOne of two qualified SP with 0.00 ERA in this span. (Cade Horton) pic.twitter.com/IZp8WViwUt
— Underdog MLB (@UnderdogMLB) August 13, 2025
Troy Melton, SP, Detroit Tigers
10% rostered
FAAB Bid: <8%
Since allowing six runs in his MLB debut, the No. 6-ranked prospect in the Detroit system has looked rather sharp in the big leagues. In his last four outings (17 1/3 innings), Melton has posted a near-perfect 0.52 ERA and a 0.58 WHIP.
Under the hood, he has generated a remarkable 3.14 xERA and a .207 xBA, which suggests he should remain a reliable contributor going forward.
Other SPs to consider: Hurston Waldrep ATL, Michael McGreevy STL
JoJo Romero, RP, St. Louis Cardinals
15% rostered
FAAB Bid: <15% if needing saves
While the 28-year-old stumbled in his last save opportunity on August 13 against the Cubs, he is currently penciled in as the clear lead-inning option with Ryan Helsley now in Queens. Since August 2, Romero has gone 3-for-4 on save opportunities and allowed three runs over this 6 2/3-inning stretch.
If you need savings badly, don't be afraid to overspend here.
Bryan Abreu, RP, Houston Astros
35% rostered
FAAB Bid: <15% if needing saves
My other reliever will likely be the most-added player this week. With Josh Hader hitting the 15-day IL with a shoulder injury and seeking a second opinion, Abreu has a clear path to take over the ninth inning in the Space City.
Abreu has been arguably the best stud man over the past few seasons and will finally be given an opportunity to shine. Through 55 innings this season, the right-hander has posted an elite 1.64 ERA, 1.05 WHIP, and an 81:25 K:BB. He is a must-add in all formats. If Hader were to miss the remainder of the season, Abreu could possess top-5 RP upside.
Other RP to consider for saves Jose A. Ferrer WSH
Fantasy Baseball Prospects to Monitor
Dylan Beavers, OF, Baltimore Orioles
15% rostered
FAAB Bid: <3%
Rounding things out will be a new prospect. The 24-year-old has continued to hit at a level at Triple-A, posting a .300/.418/.517 line with 14 doubles, 18 home runs, and 22 stolen bases.
With the Orioles far out of the playoff picture and having shipped many outfielders to San Diego, Beavers has a clear path to playing time. Given his ability to contribute to all five categories, he is worth a spot on your bench in standard formats.
Other prospects to monitor: Samuel Basallo BAL, Kristian Campbell BOS
More Fantasy Baseball Waiver Wire Advice
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