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Mike's fantasy baseball waiver wire hitters to add as category boosters for Week 21 of 2025. His top hitters to pick up or stream for HR, RBI, SB, AVG, and runs.
Welcome back to our Fantasy Baseball Waiver Wire Hitters - Category Boosters column for Week 21 of the 2025 MLB season. We are in the thick of it now, and seasons can be won or lost with our waiver wire additions.
As we prepare our teams for the stretch run to the playoffs, what do you need to get from the waiver wire to secure our spots? Do you need more home runs and steals? Do you need batting average help? We have you covered every week in this article.
We will aim to give you three options for each of the five offensive categories in a standard five-by-five league. Our rule: All hitters will be listed according to their percentage of rostered players on Yahoo!, with a maximum of 50 percent. Let's look at names that might be under the radar, but who can help you now.
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Runs Scored (R) - Fantasy Baseball Waiver Wire Boosters
Sal Frelick, OF, Milwaukee Brewers (43% rostered)
Despite the lack of metrics supporting it, Frelick has experienced a breakout season. He has established career highs in home runs (nine) and RBI (49), stealing 18 bases, and scoring 60 runs. Over the last two weeks, he has scored 11 runs while hitting a robust .318.
Chandler Simpson, OF, Tampa Bay Rays (33% rostered)
People seem not to have a clear vision of Simpson, as he is a free agent in two-thirds of Yahoo leagues. He has hit .301 with 24 stolen bases in 2025, so he is helping you there despite being a literal zero in power. Simpson has seven runs scored and two steals in the last week.
Daulton Varsho, OF, Toronto Blue Jays (17% rostered)
Varsho has shown that he can be productive when he is healthy, playing great defense, and swatting 13 home runs in only 38 games. He is never going to hit for a high average, but he helps in the runs scored department, where he has six runs in his last week of games.
Home Runs (HR) - Fantasy Baseball Waiver Wire Boosters
Miguel Andujar, 3B/OF, Cincinnati Reds (34% rostered)
Andujar makes his way to a new team and keeps hitting. Surprised? The veteran is hitting .407 with three home runs over the last two weeks, covering 36 at-bats. He is batting cleanup on a Reds team scratching to try and get to the playoffs.
Pay attention because he is also getting some shots at first base, so he could add another position eligibility to his repertoire this season, which makes him even more useful.
Lenyn Sosa, 1B/2B/3B, Chicago White Sox (32% rostered)
Sosa is a good player, flying under the radar in most fantasy leagues. Savvy players are starting to catch on, though. He is hitting a useful .273 with 17 home runs and three position eligibility. Sosa has hit five home runs in the last two weeks, three over the last seven days.
Check out his Statcast data below. You can see how his power has grown with a chance at daily at-bats. Sosa is a useful player who should be on far more rosters.
Colby Thomas, OF, Athletics (6% rostered)
Thomas is a name to know if you need outfield help. He has earned more time in a somewhat crowded outfield picture for the Athletics. He has all three of his home runs over the last two weeks. If he keeps getting that playing time, he will hit homers.
Runs Batted In (RBI) - Fantasy Baseball Waiver Wire Boosters
Spencer Steer, 1B/OF, Cincinnati Reds (47% rostered)
Steer was a popular bounce-back candidate early in draft season, even amidst the reports that his shoulder was not 100% healthy. He got off to a terrible start and found his way to the waiver wire. Steer has battled back and has 20 RBI since the All-Star break.
Despite a poor batting average, Steer knocks in a plethora of runs. He has knocked in nine runs over the last 10 days, and he plays every day for a team in contention for a playoff spot, so the at-bats will be there.
Lourdes Gurriel Jr., OF, Arizona Diamondbacks (46% rostered)
Usually only considered as an afterthought in drafts, Gurriel is putting together a nice season. He gives a nice mix of speed and power, and is driving in runs at a high clip the last two weeks, with 13 RBI. On the season, he now has 16 home runs and 10 stolen bases.
Look at his box below, and you can see that he offers a nice balance, even though the batting average is mediocre. If you need outfield help this week, consider Gurriel.
Ben Rice, C/1B, New York Yankees (44% rostered)
This may be the most staggering Statcast data on that entire page. Just look below and see what Rice is doing. When you see data like this, it seems just a matter of time until the results follow. Last weekend, he had a game with a homer and seven RBI.
Rice is hitting .317 with three home runs and 11 RBI over the last two weeks, and doing more with his growing playing time in New York. Add in that he has catcher eligibility, and you have potential fantasy gold.
Stolen Bases (SB) - Fantasy Baseball Waiver Wire Boosters
Dylan Crews, OF, Washington Nationals (47% rostered)
Crew quietly came back last week, and it felt like fantasy players had forgotten about the top prospect in Washington's system. Crews should have ample runway for the rest of the season to build a stake for a starting job in 2026.
Crews figures to get a green light when he gets on base, which has been a bit of a struggle for him. Give him time. He is a week back from a two-month IL stint, and he did steal a base in his first game back last week. Give him a shot if you're desperate for speed.
Jose Caballero, 2B/3B/SS/OF, New York Yankees (13% rostered)
Everyone knows Caballero runs; he leads the game with 39 steals this season. What you may not know is that he is getting more playing time lately, starting games at shortstop, third base, and outfield over the last week for the Yankees.
The veteran has stolen four bases over the last week due to that uptick in playing time. Don't be fooled by his measly .237 batting average. Look at the OBP, which is 100 points higher at .337 with a terrific 12% BB%. He can help you if you look deeper.
Tyler Freeman, 2B/SS/OF, Colorado Rockies (12% rostered)
Freeman is another useful player putting together a quietly good season on a moribund team. He is hitting leadoff while having eligibility at three positions. He has 16 stolen bases in 2025, and is hitting a helpful .297. In deep leagues, he is a good guy to roster.
Batting Average (AVG) - Fantasy Baseball Waiver Wire Boosters
Isaac Collins, OF, Milwaukee Brewers (39% rostered)
As stated here almost weekly, I love Collins and will find a place for him in every article until he is rostered above 50%. He just keeps hitting. A recent cold streak notwithstanding, he is hitting .31o in August with two homers, 15 RBI, two steals, and 14 runs.
He is hitting sixth in a lineup that manufactures a ton of runs. Collins should be rostered in far more leagues.
Noelvi Marte, 3B/OF, Cincinnati Reds (29% rostered)
Marte seemed forgotten about when he was hurt in early May, finding his way back to the waiver wire. Yet upon his return, he has hit. Marte is batting .344 in August with three home runs and 11 RBI, and has even chipped in a stolen base.
He does have third base eligibility, but manager Terry Francona has found at-bats for Marte by playing him in right field. The playing time should continue, and we know this guy can hit.
Joey Ortiz, 3B/SS, Milwaukee Brewers (17% rostered)
Ortiz had become a punchline in fantasy leagues with a disastrous start to the season, but look at what he has done over the last few weeks. Ortiz is the starting shortstop on the best team in baseball, and he is hitting .354 with 12 RBI and 14 runs scored in August.
We don't talk enough in fantasy circles about the fact that players who are outstanding with the glove and have some speed will find their way into major league lineups. Look at his turnaround this past month, where he is annihilating fastballs.
I hope this helps you out! Good luck and happy hunting, RotoBallers! You can always message me @mdrc0508 on X to complain about my picks or make other suggestions!
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