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Five hot fantasy baseball waiver wire pickups, streamers, and sleepers for Week 8 (2026). Undervalued hitters outperforming their ownership percentage and should be more widely owned.
Welcome, RotoBallers, to another edition of our bargain basement hitters. In this weekly column, we take a look at five of the hottest hitters in baseball (who are rostered in 25% or fewer of Yahoo leagues) and determine whether they were worth picking up.
This week, we will look at some intriguing power options at the corner infield position, including a former high-end slugger in Texas and a potential post-hype breakout in Queens.
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Brett Baty, 1B/2B/3B/OF, New York Mets
15% rostered (Yahoo)
Brett Baty has shown flashes of upside at times during his career, but has rarely been a consistent weekly option for fantasy over an extended period. Last season, Baty appeared to put together a career season, launching 18 long balls while carrying a solid .254/.313/.435 line, which made him a reliable No. 5 outfielder/utility option in most standard formats.
However, since the start of May, Baty has been enjoying one of the most productive stretches of his career, and could be showcasing that there is another level that his production can reach.
Over his first 31 games of the campaign, Baty was off to a very sluggish start, carrying a .207/.265/.304 line with just four doubles, one home run, and a 28:8 K:BB. However, over his last 15 games (since May 3), Baty has posted a much higher .269/.356/.442 with three doubles, two home runs, and improved 17:6 K:BB.
Is this recent surge significant or nothing more than a hot surge in the batter's box?
Since the start of May, Baty has made significant progress against two pitch types, fastballs and off-speed. In April, Baty generated a .293 xwOBA and a .140 xwOBA against both of these pitch types. However, since the turn of the calendar, the former 12th overall pick has raised these numbers to a .346 xwOBA and an elite .468 xwOBA.
As shown below, this improvement is quite drastic and suggests Baty has made major strides at the dish.
More importantly, his surface-level stats are right in line with his high-end underlying marks, suggesting he is earning this production. Per Baseball Savant, Baty has generated a .393 wOBA on the surface against fastballs and a .359 wOBA against off-speed pitches, both well above average, with his production against off-speed pitches leaving room for further growth.
Even though his production against breaking balls has remained stagnant, he is hitting fastballs and off-speed pitches at a much higher rate, which will continue to set him up for success.
From a batted-ball perspective, Baty has actually lowered his ground-ball rate from 51.0% to 45.9% this season and raised his fly-ball rate by one point, which currently sits at 22.1%. While his Pull AIR% has dropped to 13.3% (which is below average), his ability to lift the ball off the ground from a general perspective is a major positive, even if his swing has yet to be fully optimized.
Overall, Baty's .239 xBA is higher than his current .229 BA, which suggests that while his slow start was very unlucky, his current pace in May may be slightly above what he projects to finish the season at. However, he continues to hit the ball hard (91.0 mph average exit velocity) and has generated a strong 74.8 mph average bat speed, placing him in the 82nd percentile, and should keep his power totals high.
He is also on pace to hold a double-digit barrel rate for the second straight season and sit with a >40.0% hard-hit rate. While he may not be a reliable source of batting average, if he maintains this pace against fastballs and off-speed pitches and continues to lift the ball while maintaining his hard-hit rates, he should be well-positioned to enjoy his first 20-home-run campaign.
Jake Burger, 1B, Texas Rangers
15% rostered
Jake Burger put himself on the fantasy map in 2024 when he launched 29 home runs for the Marlins while bringing in 76 runs and scoring another 68. However, since this campaign, Burger has yet to reach this level of production and has actually seen a gradual decrease in each season.
In 2025, Burger posted a .236 AVG with just 16 long balls over a 103-game sample after missing time following a demotion to Triple-A. As a result, Burger was nothing more than a fourth-round lottery ticket in 2026 as his playing time was not even guaranteed, given that the Rangers were not afraid to open him the previous season.
Fortunately, Burger has already begun to rebound and is once again showing his near 30-HR upside.
Through the first 46 games of the campaign, Burger has held a .239 AVG but has gone deep eight times while totaling an impressive 32 RBI (fifth most in the American League) and scored 19 runs. Looking at his underlying metrics, it appears that Burger is getting a bit lucky with his production, as most of his metrics are down even relative to his 2025 marks.
So far, Burger has generated a low 9.8% barrel rate, the first time in his career he has had a sub-double-digit rate on this statistic. Additionally, Burger's hard-hit rate of 46.8% would be his lowest since 2022, and his max exit velocity of 113.6 mph would also mark the lowest of his career.
When looking at his production against specific pitch types, his profile continues to suggest major concerns. Even when comparing it to his down season in 2025, Burger's xSLG against fastballs and off-speed pitches has declined significantly, while it has only slightly increased against off-speed pitches.
However, even though he is not impacting the ball as hard, Burger has instead further optimized his swing. Through the first two months of the 2026 season, Burger has generated an elite 23.6% Pull AIR%, which would be the best of his career and is currently among the highest in the sport.
Even though he is not generating consistent hard contact, he is hitting the ball efficiently, which has kept his home run totals afloat.
While playing in a park like Globe Life Field will always suppress his home run totals, given that his swing is far more effective than ever, Burger can afford to lose some raw power and still not see his fantasy production decline.
While he is not a reliable source for batting average, his modified swing should keep him in a prime position to not only return to his 25-HR floor but also potentially push for a 30-HR season as he continues to see every day at-bats.
His home run total should also continue to make him a prime option for RBI on the waiver wire, which should only improve once Wyatt Langford and Corey Seager return to the starting nine.
Jake McCarthy, OF, Colorado Rockies
10% rostered
The next two names we will spotlight are both on the same roster. After looking at some power options, let's shift gears and discuss a batting average/speed option in the outfield.
Throughout his time as a Diamondback, McCarthy has primarily been known for his speed, especially in the fantasy realm. From 2022 through 2024, McCarthy swiped at least 20 bags in each season and hit above .280 in two of those campaigns as well.
However, in 2025, McCarthy appeared in just 67 games and posted a career-low .204 AVG with only six stolen bases, which put him off the fantasy radar heading into 2026.
With a change of scenery in Colorado, McCarthy has not only begun to rekindle his swing but also produce fantasy-relevant numbers at the dish. Through his first 38 games with the Rockies, the 28-year-old has held a .289/.346/.464 line with two home runs and eight stolen bases.
He has spent most of his time in left and center field and has just recently begun to face left-handed hitters, making four starts against southpaws since May 10. Can managers trust McCarthy to go forward with his recent increase in at-bats?
Even though McCarthy had a down year in 2025, speed was never the issue. In 2026, the outfielder has continued to showcase incredible speed, posting a 98th percentile sprint speed, which pleases in an elite class of hitters.
However, what McCarthy has improved is his quality of contact. So far, the 28-year-old has generated an 89th percentile .2897 xBA, which suggests his current.289 BA is well earned and may not drop much during the season. He also generated an above-average .335 xwOBA and a 36.3% LA Sweet-Spot%, both of which are on pace to be the highest of his career.
While his low 11.3% Pull AIR% does keep his power totals low, he is beginning to lift the ball far more effectively, generating a 47.5% ground-ball rate, which would also make it the lowest of his career.
Managers looking for power should not target McCarthy, but the Virginia product is an elite source of batting average and speed. Given Brenton Doyle's early season struggles, McCarthy could be in a position to see an everyday role, either in left or center field, which would give him 25+ SB upside. If you need speed, do not wait to grab McCarthy off the waiver wire.
TJ Rumfield, 1B, Colorado Rockies
10% rostered
The other corner infielder we will spotlight also has some sneaky power upside. Rumfield was not on the draft radar of many in the spring, but ultimately claimed the starting first base job in Colorado and has looked quite comfortable during his first stint in the big leagues.
Over his first 48 games in the majors, Rumfield has held a .270/.347/.431 slash line with eight doubles and six home runs. He has struck out at a low 15.6% rate and drawn walks at a 9.4% rate.
Since May 1, he has been even more productive at the dish, holding a .283/.377/.467 line with a .843 OPS. Can the young slugger maintain this pace?
When looking at his batted-ball metrics, Rumfield's rookie season could quietly be very productive. Per Baseball Savant, the former 12th-round pick has generated a .272 xBA, .350 xwOBA, and a .450 xSLG, all of which are in the 73rd percentile or higher among qualified hitters. He has also generated an above-average barrel rate and, more importantly, has a very optimized swing.
As we have noted in this edition of this column and in previous weeks, hitting the ball effectively is just as important as hitting it with raw power. Rumfield is connecting on both ends. He has generated an elite 40.4% LA Sweet-Spot, putting him in the 90th percentile, and added a stellar 23.4% Pull AIR%.
When looking at his production against all three pitch types, his expected marks are right in line with his face-value statistics, suggesting he is not outperforming his current pace or in danger of regressing.
Rumfield's profile is very inspiring, and he is worth picking up in all standard leagues. The young bat has even more upside during any home stand at Coors Field.
Keibert Ruiz, C, Washington Nationals
5% rostered
The final name we will spotlight this week is our backstop, Keibert Ruiz. The catcher position has recently been decimated by injuries as both Drake Baldwin and Ryan Jeffers joined Cal Raleigh on the injured list this week, leaving many managers without a real backup option or even a true No. 2 option in two-catcher leagues.
Enter Keibert Ruiz. Ruiz put together two solid seasons in 2023 and 2024 and was on the low-end C1 radar in both campaigns. During these two seasons, Ruiz averaged 15.5 HRs per season with a .245 AVG, 62 RBI, and 50 runs. However, in 2025, Ruiz took a step back, spotting a .247 AVG with just a mere two round-trippers over a 68-game stint.
While Ruiz's current stat line does not jump off the page (.236/.255/.483), he has begun to heat up at the dish. Since May 1 (nine games), Ruiz has held a strong .333/.343/.788 line with six doubles and three home runs. Even though he does not play as a true "No. 1" catcher, he is making the most of his timeshare.
Currently, under the hood, Ruiz has generated a modest .247 xwOBA, .201 xBA, and a .340 xSLG, which does not instill much confidence. When looking deeper at his performance against specific pitches, managers can easily spot flaws in his recent surge.
As shown below, Ruiz has greatly outperformed his expected metrics in May, suggesting that regression could hit him in a big way at the turn of the calendar. His surface-level wOBA against fastballs is nearly 300 points higher than the expected mark, and his production against off-speed pitches is nearly 200 points higher than it "should be."
However, he is still finding success due to his incredible 36.8% Pull AIR%. During the 2023 and 2024 seasons, he posted an elite 25.7% Pull AIR% across these two campaigns, indicating he can hit the ball effectively over extended periods. However, his current mark is very unstable and should gradually decline as he logs more at-bats.
While he has shown he can pull the ball for power, during the 2023 and 2024 seasons, he was impacting the ball at far more consistent rates than he is now. While he could still push for a 10-15 HR season, he projects to be a batting average liability, which makes him best left for deeper two-catcher leagues.
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