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Three top fantasy baseball prospects - Karson Milbrandt, Franklin Arias, Jack Wenninger - that can make big impacts. These MLB prospects are waiver wire pickups or stashes.
Every season, fantasy managers see high-end prospects earn the call to the majors and immediately emerge as must-start options for fantasy.
In this piece, we will spotlight some emerging prospects at the Double-A level who could be in the mix for a second-half debut and a pitcher at Triple-A who is quickly appreciating his MLB debut.
Should fantasy managers stash these high-end prospects? Let's dive in!
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Karson Milbrandt, SP, Miami Marlins
Current Level: AA
Availability: 5% rostered
2026 AA Stats: 47 IP, 1.34 ERA, 1.00 WHIP, 70 SO, 17 BB
The Marlins seem to have a never-ending supply of young pitchers in their farm system, as you may not have even heard of Karson Milbrandt until now, thanks to Robby Snelling, Thomas White, and Braxton Garrett attracting the majority of the attention in the minors this year. However, with injuries to Snelling, White, and Eury Perez, suddenly, Milbrandt could be close to getting his chance.
Through his first eight starts in Double-A this season, the 22-year-old posted a 1.06 ERA and 0.90 WHIP with a 39.1% strikeout rate, which are numbers that are hard to ignore. He had gone three straight starts without allowing a run through six innings each, with a whopping 32 strikeouts over those 18 innings.
It's time we talk about Karson Milbrandt as a possible Top-100 overall prospect.
Saturday: 6 IP, 3 H, 0 ER, 0 BB, 11 K
Season: 7 GS, 36.1 IP, 1.24 ERA, 0.91 WHIP, 8.7% BB, 37% K, .168 BAA
Deep arsenal, can miss bats, & has trimmed the BB%.#FightinFishpic.twitter.com/7fLKikExfw
— Eric Cross (@EricCrossMLB) May 17, 2026
While he did regress a bit on Saturday, allowing two runs on seven hits and three walks in 4 ⅔ innings, he still showcased his strikeout stuff with seven punchouts. While an immediate promotion probably isn’t imminent, considering he’s still in Double-A and wasn’t considered a can’t-miss prospect before the season, Milbrandt has certainly put himself on a trajectory for a potential 2026 debut.
The right-hander features a fastball that touches the high 90s, along with a slider, cutter, and curveball that all work well together to generate a ton of whiffs. He also throws a changeup occasionally that does not grade out as well, but it's something that can be improved upon as he continues to develop.
Earlier this week, the Marlins promoted him to Triple-A, setting him up for a potential first-half MLB debut.
-Written by Jeremy Heist
Franklin Arias, INF, Boston Red Sox
Current Level: AA
Availability: 5% rostered
2026 AA Stats: 41 G, .331/.402/.624, 8 2B, 12 HR, 4 SB
The Red Sox signed Arias as an international free agent out of Venezuela in 2023. He fetched a $525,000 signing bonus and has already reached Double-A while emerging as the consensus No. 1 prospect in the Red Sox' farm system.
Arias is a high-floor prospect with All-Star potential. He's a plus defender who offers tremendous reliability at shortstop thanks to his accurate arm and ability to get the out even when hurried. He has an advanced approach at the plate with a beautiful swing that produces plenty of power and relatively low whiff rates.
It may seem like Arias is undersized at 5-foot-11 and 170 pounds, but he squares up the baseball so often that he consistently posts high exit velocities. This has allowed him to tap into more power than ever this year — his 12 homers in 2026 are already a career-high, and it's only May — and his relative quickness makes him a threat for doubles and triples.
Since he's still in Double-A, most fantasy managers haven't quite caught on to the upside he offers. It's fair to wonder whether he'll reach the majors by the end of the season, but with more than four months remaining, we wouldn't be surprised to see him make his MLB debut in 2026. As a result, he's a worthwhile shortstop stash in redraft leagues.
Franklin Arias with his 2nd home run of the game!
Arias is now up to 🔟 home runs this season.#DirtyWater pic.twitter.com/sVav8R7PpI
— Eric Cross (@EricCrossMLB) May 22, 2026
- Written by Andersen Pickard
Jack Wenninger, SP, New York Mets
Current Level: AAA
Availability: 5% rostered
2026 AAA Stats: 45 IP, 2.80 ERA, 1.33 WHIP, 46 SO, 25 BB
With Jonah Tong recently promoted to the major leagues, Jack Wenninger enters Week 10 as the clear next-best option in the Mets pipeline. However, while Tong stumbled his way through the start of the Triple-A campaign, Wenninger excelled, which makes him an intriguing target.
After spending the 2025 season with Double-A, the Mets gave the Illinois product the green light to open the 2026 campaign with Triple-A Syracuse. During his first 41 innings (nine starts) with the top club, Wenninger has looked rather sharp, posting a stellar 2.20 ERA with a 1.22 WHIP. In this stint, Wenninger has continued to showcase above-average strikeout skills, totaling 44 strikeouts, but has struggled to show steady command, walking 24 of the hitters he has faced.
In his most recent outing, Wenninger stumbled, serving up nine hits over four frames with four earned runs.
His ratios have begun to climb over his last two outings, where he has given up eight runs. This is a stark difference as the right-hander allowed only four total earned runs over his first 33 1/3 innings of the campaign.
Last summer, his command was not as much of an issue, as he walked only 42 hitters in 135 2/3 innings at Double-A. Overall, his current walk rate of 13.8% is nearly double that of his 2025 mark (7.6%).
While Tong will likely earn spot starts before Wenninger, he remains a viable option in deeper 12+ team leagues. If he can show improved command and work himself out of this recent slump, he could put himself in a great position to spend most of the second half in Queens on a Mets team that will likely be heading toward a "re-tool."
Jack Wenninger a Top Arm to Stash in Fantasy Baseball? https://t.co/YqKUp9MuF9
— RotoBaller MLB (@RotoBallerMLB) May 19, 2026
2026 Prospect Fantasy Baseball Redraft Stash Rankings
Who are the top fantasy baseball prospects to know? Check out our latest 2026 prospect fantasy baseball rankings which are updated regularly by Eric Cross:
Promoted Last Week: Gage Jump (ATH), Jacob Gonzalez (CHW), Ryan Ward (LAD), Charles McAdoo (TOR)
Honorable Mentions (Hitters): Lazaro Montes (SEA), Harry Ford (WAS), Ryan Clifford (NYM), Zac Veen (COL), Deyvison De Los Santos (MIA), Hector Rodriguez (CIN), Blaze Jordan (STL), Jacob Melton (TBR), Michael Arroyo (SEA), Jonathon Long (CHC), Joshua Kuroda-Grauer (ATH)
Honorable Mentions (Pitchers): Hagen Smith (CHW), Brody Hopkins (TBR), Jack Wenninger (NYM), Hunter Barco (PIT)
| Rank | Player | Position | Team | ETA |
| 1 | Edwin Arroyo | 2B/SS | Reds | Now |
| 2 | Kaelen Culpepper | SS | Twins | June |
| 3 | Kade Anderson | SP | Mariners | July |
| 4 | River Ryan | SP | Dodgers | June |
| 5 | Joshua Baez | OF | Cardinals | July |
| 6 | Max Clark | OF | Tigers | August |
| 7 | Charlie Condon | 1B | Rockies | July |
| 8 | Braden Montgomery | OF | White Sox | July |
| 9 | Jett Williams | SS/OF | Brewers | July |
| 10 | James Tibbs III | OF | Dodgers | June |
| 11 | Luis Lara | OF | Brewers | June |
| 12 | Cooper Pratt | SS | Brewers | July |
| 13 | Cole Carrigg | OF | Rockies | June |
| 14 | Yohandy Morales | 1B/3B | Nationals | June |
| 15 | Walker Jenkins | OF | Twins | August |
| 16 | Elmer Rodriguez | SP | Yankees | July |
| 17 | Ralphy Velazquez | 1B | Guardians | August |
| 18 | Thomas White | SP | Marlins | July |
| 19 | Carlos Lagrange | SP | Yankees | July |
| 20 | Spencer Jones | OF | Yankees | July |
| 21 | Aidan Miller | SS | Phillies | August |
| 22 | Abimelec Ortiz | 1B | Nationals | July |
| 23 | Jaxon Wiggins | SP | Cubs | July |
| 24 | Kemp Alderman | OF | Marlins | July |
| 25 | Jordan Lawlar | INF/OF | Diamondbacks | July |
Who Should I Pickup Fantasy Baseball Tool
Trying to decide who to pick up off the waiver wire? Check the Who Should I Pickup tool:
Compare up to four players and we'll tell you who to pickup...
2026 Player Decisions. Looking to pick up someone else instead? Today's focus is on specific players like Karson Milbrandt, Franklin Arias, Jack Wenninger, Jared Jones, Samuel Basallo, Josh Jung, Ryne Nelson, Cam Smith, Christian Scott, David Sandlin, Zack Gelof, Cade Cavalli. These are some common searches for 2026 fantasy baseball waiver wire pickups.
Using The Tool. This is a simple tool but very powerful. The first step is to enter the player names that you want to compare. In the first box, search for the first player's name. In the second box, search for the second player's name. Compare up to four MLB players at once, and then click the Who To Pickup? button to see who the recommended waiver wire pickups are based on fantasy baseball rankings, projections, and more.
Improvements For Who Should I Pickup? You may have noticed, our Who Should I Pickup? tool has gotten an overhaul. We've added lots of great features for you to give you as much information as possible to win on the waiver wire in 2026. You'll see MLB player tiles with stats, projections, and a slick new interface. We hope you enjoy!
How It Works. Our RotoBaller staff puts together their weekly fantasy baseball waiver wire rankings and projections based on their research, and updates them constantly throughout the week. That information is the core data that is powering the decision-making in this tool. When you search for player names, you will only see those players who are ranked.
Popular Player Comparison Searches - Who To Pickup
Looking to pick up someone else instead? Below are some popular searches and comparisons from our Who To Pickup tool for 2026 for players like Karson Milbrandt, Franklin Arias, Jack Wenninger, Jared Jones, Samuel Basallo, Josh Jung, Ryne Nelson, Cam Smith, Christian Scott, David Sandlin, Zack Gelof, Cade Cavalli:
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