Hitter Fantasy Baseball Breakouts - Risers to Watch and Waiver Wire Outlooks (Week 21)

Jarod's hitter fantasy baseball breakouts, sleepers, and risers to watch for Week 21 of 2025. His list includes waiver wire outlooks and underachieving hitters so far.

Welcome back to my Fantasy Baseball Breakout Hitters article for Week 21 of the 2025 MLB season. The focus of this article is to highlight players who could be on the verge of a breakout, citing current active hitting streaks along with recent leaders in batting average, stolen bases, and isolated power (ISO).

This week, we'll check in on some hot names like Tyler Soderstrom, Giancarlo Stanton, and Jakob Marsee. We'll also take a look at another guy who is posting better-than-expected results who could be a regression candidate.

Who should fantasy managers look to grab off the waiver wire or even plug into their DFS lineup this week? Let's check it out below!

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Hit Streak Leaders

Data through 8/13

Tyler Soderstrom (13 games)

Soderstrom tops the list this week, now with the longest hit streak in the majors at 13 games. The streak has been peppered with his usual power stroke, tallying six doubles and three home runs during this stretch in which he's gone 17-for-54 (.315).

Sodey Smash 😤 pic.twitter.com/38U1r9xaK7

— Athletics (@Athletics) August 12, 2025

He's also collected 11 RBI and scored eight times during the hit streak, so he's been good for season-long managers and DFS players alike.

The former first-rounder is now slashing .262/.333/.469 on the year with 22 home runs, a .346 wOBA, and a 120 wRC+ in 122 games.

The left-handed slugger is rostered in 86 percent of Yahoo! leagues, so you won't find him on most waiver wires, but if you're considering using him for DFS, make sure it's versus a right-handed starter.

The 23-year-old is doing most of his damage against them this year, recording a .273/.356/.507 slash line with a .370 wOBA and 136 wRC+ against them, compared to a .224/.248/.337 slash line with a .255 wOBA and 57 wRC+ against southpaws.

Highest Batting Average Last Seven Days

Data through 8/13, minimum 13 at-bats

Giancarlo Stanton (.529 BA)

Since coming off the injured list in June, Stanton has picked up where he left off last postseason, not only hitting for power, but also for average. Last postseason, the former MVP hit .273 with seven home runs in 14 games during New York's playoff run.

A four-hit game highly influenced this past week's batting average of .529, but even so, the 35-year-old has collected at least one hit in 14 consecutive games in which he started (not counting pinch-hit appearances), and is hitting .299 through 43 games this year.

The 6-foot-6 slugger did not hit a home run in his first 12 games of 2025, but has 12 in his last 31 games, and is now the owner of a .401 wOBA and 161 wRC+.

Greatness starts with G. @Giancarlo818 💣 pic.twitter.com/x77uy8AODO

— New York Yankees (@Yankees) August 13, 2025

The five-time All-Star is just 49 percent rostered, but managers looking for home runs and RBI should consider picking Stanton up, and may even gain the unexpected benefit of a solid batting average as well.

Highest ISO Last Seven Days

Data through 8/13, minimum 13 at-bats

Brice Turang (.667 ISO)

Turang hasn't been associated with hitting for power, hitting just 13 home runs in his first 292 MLB games, but is already up to 12 home runs so far this year, with four of them coming in the last week alone.

Brice Turang extends the @Brewers lead with a solo tank! pic.twitter.com/YNVQfYu28O

— MLB (@MLB) August 13, 2025

At first glance, one might think he can't keep it up, but when looking deeper, perhaps he can. In 2023 and 2024, Turang's bat speed came in at the 11th and second percentiles, respectively. That has increased to the 20th percentile this year.

Increases in bat speed have generally seen power increases, and the 25-year-old is sailing past previous career highs in barrel rate, hard-hit rate, and average exit velocity.

Will he average four home runs per week from here on out? No. But can he get to 15-plus? Yes. Combined with a pace for 90 runs scored and 30 stolen bases, he can be a sneaky-good DFS play who can hit both lefties and righties for a suddenly potent Milwaukee offense.

Kyle Manzardo (.625 ISO)

Manzardo has been a solid source of power all season, with the three home runs he hit this past week bringing his 2025 total to 21.

Looking at his batting average of .242, and you might be somewhat reluctant to use him in season-long leagues, especially if you're trying to gain ground down the home stretch; however, if you looked at that number in a vacuum, you'd be misled.

The 25-year-old is hitting .367 since July 21, a stretch of 19 games in which he's gone 22-for-60 with three doubles, six home runs, 16 RBI, and nine runs scored.

He's still striking out at an elevated 27.8 percent rate over that time, which could mean that the average will eventually dip. However, it's still a palatable rate for a power hitter who just so happens to be rostered in only 19 percent of leagues.

Most Steals Last Seven Days

Data through 8/13

Jakob Marsee (five SBs)

Marsee has been making headlines for his bat, which included a seven-RBI performance on Wednesday, but his calling card in the minors was his speed. In last week's article, I mentioned, "If you're searching for steals at this juncture in the fantasy season, Marsee could be your guy."

Jakob Marsee 2-HR game!

He has a 1.408 OPS through his first 13 Major League games 👀 pic.twitter.com/8XAgrBJpll

— MLB (@MLB) August 14, 2025

Now, he's swiped the most bags in the last week with five stolen bases. Three of them came in one game, but that shows you what kind of potential he has on the basepaths.

The 24-year-old's rostered percentage has increased 21 percent since last week, now up to 44 percent rostered, which is getting closer to an appropriate level. But if you're searching for steals this late in the season, his ability to draw walks (18.8 percent) should allow additional steals even if the bat goes cold.

xBA Underachiever

Data through 8/13

Gleyber Torres (.341 vs. .386)

Frustrated Gleyber Torres managers who have seen him go 4-for-31 (.129) over the last week, hang in there; he could end the season on a high note.

The 28-year-old has an xwOBA that is 45 points higher than his actual wOBA, and although he's batting a respectable .265, his xBA of .292 suggests things should be going much better for the Venezuelan.

His contact rate (83.9 percent), strikeout rate (14.3 percent), swinging-strike rate (6.7 percent), and chase rate (17.3 percent) are all career bests, all while registering a 12.8 percent walk rate that is 91st percentile.

Look for the three-time All-Star to go on one last hot streak to finish out the year, which could start with Minnesota's Jose Urena (4.97 ERA, six HRs in four starts) on Friday or Zebby Matthews on Saturday (yielded three home runs in last start).

xBA Overachiever

Data through 8/13

Shea Langeliers (.363 vs. .331)

As a career .215 hitter coming into 2025, it's a bit surprising to see Shea Langeliers with a .272 batting average at this stage of the season. With a strikeout rate that has improved from 27.2 percent to 18.4 percent year over year, it seems he's made an adjustment that allowed him to register a career high contact rate while maintaining a 30-ish home run pace.

Still, the 27-year-old is hitting .382 since July 18, and while that is terrific, he's probably due for some regression, even with his newfound approach that has allowed him to hit for average.

Couple that with an xwOBA that is 32 points lower than his actual wOBA, and it backs up that belief. Hopefully, the power-hitting backstop doesn't leave fantasy managers high and dry at this crucial point in the season, but be on the lookout for a slowdown.

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