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Five hot fantasy baseball waiver wire pickups, streamers, and sleepers for Week 12 (2026). Undervalued hitters outperforming their ownership percentage and should be more widely owned.
Welcome, RotoBallers, to another edition of our Bargain Basement Hitters. We are already past the halfway point in June, and throughout the first half, we have seen many waiver wire hitters emerge as must-start assets. Through this series, we have spotlighted the "breakout" of Dillon Dingler, TJ Rumfield, and Brayan Rocchio before they became must-add players.
This week, we will spotlight two players in Miami and a young prospect in San Diego, among others. As always, the names listed here are available and rostered in 25% (or fewer) of all Yahoo leagues.
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Heriberto Hernandez, OF, Miami Marlins
5% rostered (Yahoo)
Hernandez made his MLB debut last summer for the Marlins and showed solid upside over his first full taste of the majors. Across an 87-game stint, the outfielder held a .266/.347/.438 line with a .735 OPS.
During this stretch, Hernandez hit 10 home runs and added 12 doubles while carrying a 71:31 K:BB. Playing time was not guaranteed heading into the season, which kept Hernandez on the waiver wire in most formats.
Over the first 30 games of this season, Hernandez really struggled at the dish, which likely encouraged any deep-league managers holding on to cut ties. Over the opening month, Hernandez held a rough .167/.268/.226 line with just one home run. However, Hernandez has not only been unable to find his footing, but has also become a regular in this Miami lineup.
Since this cold slump, Hernandez has posted an elite .327/.351/.618 line with an impressive .969 OPS. He has launched five round-trippers over this short 17-game stint and tallied 13 RBI with nine runs.
Should managers look to trust Hernandez going forward?
His overall .230/.299/.381 line does not instill much confidence and suggests his recent surge is nothing more than a flash in the pan; his underlying metrics are rather impressive, though. Currently, the 26-year-old sophomore has generated a .350 xwOBA, .264 xBA, and a .468 xSLG, all of which would place him well above the average marks.
He has also generated a 91.7 mph average exit velocity and 48.5% hard-hit rate with an elite 74.8 mph average bat speed. All of these metrics suggest that his early season play was highly unlucky.
When looking at his performance against certain pitch types, managers can easily spot where Hernandez should see some prominent positive regression. As shown below, when facing fastballs, the outfielder has posted a low .229 BA but "should" have generated a .288 xBA. When facing breaking balls, his .373 SLG is much lower than the .436 xSLG under the hood.
Another reason to be intrigued by Hernandez's profile is his optimized swing. The key to finding potential breakout hitters is to look beyond their hard-hit metrics and see how they impact the ball. If a player is hitting the ball hard but not pulling it, they will not hit for a high total of home runs, no matter how hard they impact the ball (see Vladimir Guerrero Jr.).
However, Hernandez may have the proper profile. So far, the young outfielder has generated an above-average 21.8% Pull AIR%. Last summer, he posted an even higher 22.4% Pull AIR%, suggesting there is room for some minor improvements. Pairing this with his high-end bat speed and hard-hit rate could set him up for a 20-HR season.
Lastly, Hernandez has quietly swept five bags this season (in comparison to just one in 2025). So far, he sits in the 84th percentile in spring speed, which could open the door for a double-digit stolen base campaign if his batting average can enjoy the expected positive regression to bolster his on-base rate.
With his growing hard-hit rates (45.4% - 48.5%), above-average Pull AIR% metrics, and high-end speed, we could look at a five-category asset in Miami. Playing time could remain an issue in the short term, but if he maintains this pace, the left field job will be his to lose.
Samad Taylor, 2B/OF, San Diego Padres
10% rostered
Samad Taylor made his MLB debut back in 2023 with the Royals, but never earned a true "full look" in the majors until this season. From 2023 through 2025, Taylor spent time in Kansas City and Seattle but appeared in just 38 games (31 of them in 2023) and posted a .205/.272/.260 line with eight stolen bases.
However, after putting together a stellar season at Triple-A El Paso, Taylor earned a call-up to San Diego. That momentum has carried over into his play. Through 10 games in San Diego, Taylor has held a .355/.412/.484 line with an .896 OPS. During this stretch, Taylor has hit one double, his first MLB long ball, and swiped three bases.
While he began his time with the Padres in a bench role, he has begun to see nearly every day at-bats in left field, which has pushed his rostership rate into double-digit territory.
The sample is small, but the 27-year-old is showing enough upside to warrant consideration. Through this short stint, Taylor has generated a stellar .295 xBA (to back up his current .355 BA) and posted a 30.0% squared-up rate. While he has not impacted the ball hard, Taylor's calling card in the minor leagues was never his raw power.
Earlier this season at Triple-A (51 games), Taylor posted a .319/.406/.500 line with seven long balls and nine stolen bases. Managers should not expect that power to translate to the majors, as he will likely finish with just around five long balls if he maintains this pace. However, he does have value in points leagues and in categories that need batting average and speed.
So far, his elite xBA and sprint speed (96th percentile) suggest he could flirt with a near .300 AVG while pushing for a 20+ SB campaign. This is a hitter who swiped 44 bags over 137 games at Triple-A Tacoma in 2025 and stole 50 over 136 games at Tacoma in 2024.
For those in points leagues, do not be influenced by his inflated 25.7% K%. He has posted a much lower 22.9% chase rate and 19.3% whiff rate, suggesting his K% should endure some prominent positive regression as he sees more at-bats.
Playing time will be key for Taylor, who has the profile to hold value in specific category builds and deeper points leagues.
Jake Mangum, OF, Pittsburgh Pirates
10% rostered
Despite being drafted in 2019, Jake Mangum was a "rookie" in 2025. Last summer, Mangum made his MLB debut with the Rays and appeared in 118 games. Over his first full year in the majors, Mangum hit .296/.330/.368 with one home run and an impressive 27 stolen bases.
Mangum would eventually move to the Steel City as part of the Brandon Lowe deal over the winter. While playing time was hard to find early in the season, the recent injury to Oneil Cruz has made Mangum a regular in the Pittsburgh lineup.
Through 54 total games, Mangum has held a .299/.350/.354 line with one home run and 13 stolen bases. However, his production has been even more impressive as of late, carrying an average of .400/.415/.520 with seven of these stolen bases (and his lone home run) over his last 15 contests.
Can the second-year outfielder of Mississippi State maintain this pace?
When looking at his metrics since June 1 (when most of his surge has occurred), managers can spot some concerning trends in his profile. When looking at his xwOBA against all three pitch types, Mangum has greatly outperformed his expected production. While this does not mean Mangum will have a major falloff (as shown by his + .300 xBA against offspeed and breaking balls), managers should expect some regression.
Overall, his .264 xBA is above average (68th percentile), but is much lower than his current .299 BA on the surface. Additionally, he sits below the 10th percentile in hard-hit rate, barrel rate, bat speed, and xSLG, which suggests he offers no upside in terms of power.
However, while his recent .520 SLG should come back down, his speed will not. He currently sits in the 94th percentile in sprint speed and is on pace to swipe 39 bags if he maintains a full-time role.
Like Taylor, those needing high-end speed with a solid average should target Mangum off the waiver wire. If looking for power, pivot to the next name.
Dominic Canzone, OF, Seattle Mariners
20% rostered
This week's source of power comes from Seattle. Canzone is on the strong side of a platoon but has continued to make the most of his somewhat limited at-bats. Through 65 games of action, the slugger has posted a .287/.357/.555 line with a .912 OPS. He has gone deep 10 times, added 12 doubles, and posted a 35:16 K:BB.
While his production is steady on the surface, managers can still find him on the waiver wire in nearly 80% of Yahoo leagues. Despite those concerns about his playing time (and lower-end cutting stats), Canzone should still be viewed as a priority target.
Even though his 29 RBI and 25 runs are relatively low on the surface, Canzone's metrics suggest there is another level of play he can reach later in the summer. Over his last 10 games, Canzone has hit three of these round-trippers while holding a 1.304 OPS. Managers should not wait much longer to pick up, as his metrics suggest this surge could be a sign of better things to come.
Currently, the 28-year-old sits in the elite class of hitters in terms of xBA, xwOBA, xSLG, barrel rate, and LA Sweet-Spot%. In this statistic, Canzone ranks at or above the 92nd percentile and has a similar hard-hit rate in the 87th percentile. His high-end 74.7 mph average bat speed puts him in the 80th percentile, and 29.2% squared-up rate is in the 81st percentile.
Additionally, if that was not enough to impress, Canzone has generated a strong 19.8% Pull AIR%, which is on par with his highest since his rookie-level mark in the 2023 season.
What has limited his upside is his ballpark. Playing in Seattle (a pitcher's park) caps his fantasy ceiling. Per Statcast, Canzone's expected HR total is nine, but he would have hit up to 15 if he were playing for the Brewers, Athletics, Dodgers, and Reds.
Even though managers should expect his ceiling to be low due to the home park and platoon role, his underlying marks suggest he should continue to remain a very productive power hitter and is worth rostering (and starting) in most five-outfielder leagues. Not many "pure" power hitters on the waiver wire will also be a plus asset in batting average.
Joe Mack, C, Miami Marlins
5% rostered
Rounding out this week's column now will be our catcher, Joe Mack. While Mack was not viewed as the team's top hitting catcher in the minor leagues (that was Agustin Ramirez), Mack has looked quite comfortable in the MLB batter's box. Through his first 33 games in the majors, Mack has posted a .255/.318/.367 line with five doubles and two long balls.
Since June 1, the rookie has been among the top catchers in fantasy, carrying a .333/.405/.576 line with both of these home runs and a .981 OPS. Is this a sign of a potential breakout? While his MLB sample is small, he has shown steady progress since joining the Marlins. As shown below, his xwOBA against all three pitch types has improved since May 1.
Also, when looking deeper at his production against each pitch type in June, managers can not only spot progress, but also signs that he may maintain this current pace at the plate.
He has generated an xBA above .300 against all three pitch types and showed improvement in whiff rate against both fastballs and offspeed pitches.
Overall, the 23-year-old had a .232 xBA and a .327 xSLG, but much of that was influenced by his sluggish start to his career in May. What managers should be paying close attention to is his Pull AIR%. In June, Mack has enjoyed a nice power surge, attributed to his impressive 17.4% Pull AIR%, as he is not impacting the ball overly hard (37.7% hard-hit rate).
His elite defensive skills behind the plate should keep him firmly in the C1 role in Miami, even when Ramirez returns to the major leagues. Those needing a No. 2 catcher should target Mack with confidence this week.
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