7 Must-Add Waiver Wire Pickups for Week 21 Fantasy Baseball (2026)

August 15, 2026

Andy breaks down his must-add fantasy baseball waiver wire pickups for Week 21 of the 2026 MLB season. Add these players now off the waiver wire and win more.

Hello, RotoBallers! Welcome back to another edition of our 7 Must-Adds ahead of Week 21 of the fantasy baseball season. While many top prospects earned the call last week, we have yet another to highlight in this edition, and also take a look at two emerging high-leverage options.

This week, we will take a look at seven players who are available in 75% of all Yahoo leagues and explain why managers should prioritize them on the waiver wire. Be sure to follow RotoBaller MLB on X for all of our league-winning content and me @A_Smith_FS.

Additionally, be sure to use discount code SMITH for 50% off any Premium Packages and gain access to our Team Sync platform with customized lineup tools, projections, and more based on your league settings. Let's dive in!

2026 Fantasy Baseball Week 21 Waiver Wire Adds

Tim Tawa, 1B/2B/3B/OF, Arizona Diamondbacks

10% rostered

The first hitter we will spotlight has positional eligibility across the diamond, making him a worthy option in all standard 12-team formats. On the season, the utility man carries a .232/.284/.379 line with a modest .663 OPS. He has gone deep six times and chipped in another six stolen bases.

However, his recent play at the dish has pushed him onto this piece.

Since August 2 (his last 11 games), Tawa has carried a sharp .310/.333/.452 line with two of these home runs and four of his six stolen bases. Prior to this surge, Tawa rarely had consistent at-bats in the majors and had a modest .715 OPS over his last 22 contests.

While his track record of success is not only large, Tawa has become a lineup regular in Arizona, which makes him worth a closer look ahead of Week 21.

The major surge in his power has been on display across all three pitch types. As shown in the visual below, Tawa has seen his xSLG across all three pitch types increase over the past month compared to his production in the opening months of the season.

The other aspect of his profile that is promising to managers is his Pull AIR%. Seeing his power begin to show on the box score (two home runs over his last 10 games) is very promising, and the underlying 17.3% Pull AIR% can open the door for a greater second-half surge.

When in the minor leagues, Tawa hit 31 home runs back in the 2024 season (142 games) and hit seven long balls over a 20-game stint in Reno this season.

Jacob Young, OF, Washington Nationals

17% rostered

The outfielder has quietly been one of the hottest hitters in the sport. Over his last 15 games of action, Young has posted a sharp .381/.481/.595 line with a high 1.077 OPS. During this stretch, Young has hit four doubles, one home run, and chipped in two stolen bases.

While his season-long stats have been solid (.248 AVG, 10 HR, 13 SB), it appears the 27-year-old could be taking a step forward in the second half. In fact, his underlying metrics suggest a late-season improvement is in play.

Per Baseball Savant, Young holds a .262 xBA with placements in the 73rd percentile and is much higher than his surface-level mark. He has also impacted the ball very effectively, as shown in the 36.5% LA Sweet-Spot% and 34.4% Squared-Up%.

However, his improvement in Pull Air% should continue to drive his home run totals down the stretch. Through 364 PAs this season, Young has generated a solid 15.1% Pull AIR%, which is a stark improvement compared to the 5.9% Pull AIR% he held in 2025. As shown below, he has also begun to improve his Pull% against both breaking balls and offspeed pitches, which could drive even further power production later in the campaign.

In addition to his rising power, Young will also be a plus asset for stolen bases, as shown by his remarkable 93rd percentile sprint speed. With an everyday role in center field, Young can be a solid power/speed contributor across all five outfield leagues down the stretch.

Cam Smith, OF, Houston Astros

20% rostered

The former top prospect may be finally putting it together. Over his last 12 contests (since July 29), the former first-round pick has posted a stellar .386/.413/.682 line with a 1.095 OPS, two doubles, three home runs and a 13:2 K:BB.

Prior to this stretch, Smith held a modest .204/.281/.359 line with 13 long balls over 107 games. While he has shown flashes of potential at times, it appears this recent stretch could be the start of his long-awaited breakout.

The major key to Smith's recent improvements is his increasing pull rates. Smith has always shown impressive raw skill, as evidenced by his 99th-percentile bat speed, but has never had consistent home run totals due to an ineffective pull rate.

However, as shown below, the former Chicago Cub draft pick has begun to pull the ball more effectively when facing breaking balls and fastballs, which has been the catalyst for his recent improvements.

The 23-year-old has also generated a high 11.9% barrel rate with a 45.7% hard-hit rate on the season. If Smith can continue to uphold the ball effectively, the right-hander could become a league-winning down the stretch.

He is a top add in all 12-team formats ahead of Week 21.

Zac Veen, OF, Colorado Rockies

10% rostered

Zac Veen made his MLB debut in 2025, but struggled over his limited stint of action. Through his first 12 games in the majors, Veen posted a rough .118/.189/.235 line with a .424 OPS. As a result, Veen was not on the radar of many entering the 2026 season, as he was not expected to earn a role in the major leagues at the time.

While he didn't earn the call until later this season, Veen was among the top hitters in the minor leagues ahead of his promotion. Through 100 games at Triple-A Albuquerque this season, Veen posted an elite .327/.402/.635 line with a 1.037 OPS. During this stretch, the former ninth overall pick from the 2020 MLB Draft hit33 doubles, launched 24 home runs, and even chipped in 18 stolen bases.

Over his last 12 games before earning the call, Veen took his play to another level as he launched eight home runs (including a three-home run effort) with a .462/.533/1.115 line.

While Veen was held out of the lineup for his first few games back in the majors, he wasted little time making an impact in his first start. On Wednesday, Veen went 1-for-3 with a long ball.

Even though Veen may not be given a full-time role, his five-category potential makes him a worth look across all standard leagues this weekend. If he were to carve out a full-time role, he could become a must-start option down the stretch.

COL - Zac Veen 2-run HR (1)

📏 407 ft | 💨 104.7 mph | 📐 26°
⚾️ 86.7 mph changeup (ARI - RHP Merrill Kelly)
🏟️ Out in 29/30 parks

COL (6) @ ARI (1)
🔺 4th#Rockies pic.twitter.com/Y27u4EMgW6

— MLB Home Runs (@MLBHRs_) August 12, 2026

Cody Bradford, SP, Texas Rangers

7% rostered

The starting pitcher we will spotlight has recently returned from injury and looks quite effective on the mound. Bradford made his MLB debut back in 2023 but was more effective in 2024, where he logged 76 1/3 innings with a strong 3.54 ERA and a main 1.01 WHIP. While he struck out just 70 batters, his elite command and a low-to-mid 1.01 WHIP make him worthy of a dynasty asset.

However, he would not make his MLB debut in 2025 after undergoing an internal brace procedure in June. After a long recovery, Bradford has returned to Texas and is once again performing quite well.

Through two starts, Bradford has logged 11 1/3 innings with a sharp 2.38 ERA and a 1.15 WHIP. In his season debut, he logged 4 1/3 shutout innings against the Giants and would follow that up with a seven-inning three-run showing against the Angels in his second outing.

Even though he has tallied just six punchouts over these two starts, the right-hander appears to be a strong option to bolster your ratios down the stretch.

Bradford is primarily a two-pitch pitcher and mixes in a third option (his slider) just 10.3% of the time. His four-seamer (45.5% usage) generated a modest .374 xwOBA with a 23.7% whiff rate. However, the pitch to know is his changeup (36.6% usage), which has generated a sharp .255 xwOBA with a similar 17.4% whiff rate.

His elite command (career 4.8% BB% in the majors) should make him an elite WHIP contributor for the remainder of the season even though he will provide high-end strikeout totals.

Justin Martinez, RP, Arizona Diamondbacks

5% rostered

A name to watch for saves is Justin Martinez of Arizona. Following the release of Paul Sewald, the Diamondbacks have relied on a mix of Brandyn Garcia, Kevin Ginkel, Juan Morillo, and Jonathan Loaisiga to operate in high-leverage situations. While Garcia has emerged as the slight favorite, Martinez appears poised to slide into this role when he heals back from injury.

The right-hander has been on the shelf after undergoing Tommy John surgery, but embarked on a rehab assignment earlier in the second half and is now on the verge of returning to the desert.

Martinez began his rehab assignment with Low-A, where he logged two scoreless frames with a 3:1 K:BB. He then moved up to Triple-A Tacoma, where he tossed another clean frame on August 11 and added another two punchouts.

Back in 2024, Martinez logged a season-high 72 2/3 innings in the desert, where he posted a tidy 2.48 ERA with a 1.31 WHIP. While the 11.7% BB% inflated his WHIP, he flashed high-end strikeout upside, posting a 29.5% K% with light saves. Before hitting the shelf in 2025, Martinez added another five saves while holding an elite 3.21 xERA, .163 xBA, and a 32.8% K%.

Seeing him improve his command in his rehab assignment is a positive sign for his outlook for the remainder of the season. Even though it may take him some time to fully climb the ninth-inning job, Martinez is best equipped to operate as the primary ninth-inning option down the stretch as they look to secure a Wild Card.

Samy Natera Jr., RP, Los Angeles Angels

3% rostered

The final name we will target is also a potential save option. With Kirby Yates and Ryan Zeferjahn now off the roster, the Angels bullpen is wide open for the final months of the season. While much of the attention has gone to Ben Joyce, who recently returned to the major leagues and earned a save this week, the name to watch is Samy Natera Jr.

The southpaw made his MLB debut this season and has yet to face any major struggles. Through his first 27 innings, the left-hander has posted a 2.00 ERA with a 0.85 WHIP. Through this stint, he has struck out 42 hitters (40.4% K%) while walking 9.6% of the batters he has faced. While his walk rate could be lower, he is allowing very weak contact.

He has generated a 1.99 xERA and a .147 xBA with a 31.4% hard-hit rate, all of which would place him in the elite tier of relievers if he were to have logged enough innings. His high-end strikeout rate is also quite sustainable, as suggested by the 37.3% whiff rate.

However, what has put him on this list are his recent improvements. While his walk rate on the season remains inflated, his command has been much stronger over the past month. Since June 24 (his last 20 2/3 innings), Natera has held a 34:4 K:BB with a 2.18 ERA and a 0.73 WHIP. Over his last three outings, he has gone 2-for-2 on saves while Joyce has earned just one save (on August 12).

While this could shift to a committee, Natera appears to have the upper hand at the time of writing. His elite strikeout production and declining walk rate will also allow him to provide fantasy value, even if the saves are not overly consistent.

Other Fantasy Baseball Waiver Wire Targets

• Griffin Conine, MIA
• Hogan Harris, ATH
• Luis Rengifo, SD
• Kade Anderson, SEA
• Joshua Baez, STL
• Dominic Canzone, SEA

More Fantasy Baseball Advice