Sneaky Fantasy Baseball Waiver Wire Pickups, Buys: Week 5 - Hot Pitchers To Sustain Success?

April 28, 2026

Andy looks at four sneaky fantasy baseball waiver wire pickups for starting pitchers in Week 5 (2026) on hot streaks, and sees if they can sustain their success.

With another week of MLB action behind us, it's time to do another deep dive and examine four hot starting pitchers that could be worth adding off the waiver wire.

This week, we will spotlight some pitchers that may not have the highest strikeout potential, but have emerged as top contributors when looking for a boost in WHIP.

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Justin Wrobleski, Los Angeles Dodgers

45% Rostered (Yahoo)

The southpaw opened the regular season in a long relief role out of the bullpen but has since claimed a full-time role in the rotation and has been nothing short of impressive. After allowing three runs and four hits over his long relief outing (four innings) on March 30, the left-hander has been one of the Dodgers' most reliable pitchers.

Over his last four starts (26 innings), Wrobleski has posted an elite 0.69 ERA with a 0.92 WHIP. He has allowed just two total earned runs while holding a modest 13:8 K:BB. While his low strikeout rate and higher walk rate are not most conducive to fantasy production, Wrobleski is getting the job done and has seen his roster mark soar, sitting at just under 50%.

The left-hander relies heavily on a two-pitch, his four-seamer and slider, which he throws for a combined 85.9% of the time. Out of this group, the four-seamer leads the way, being deployed at a 52.3% rate, with his slider coming in at a lower 33.6% rate.

Compared to last summer, his four-seamer has dropped in velocity (96.0 mph to 93.6 mph), but that has not affected the results, as this pitch has generated a strong .231 wOBA with a .211 BA. While the .294 xwOBA and .257 xBA under the hood suggest he could face some regression, the marks are not overly different.

Similarly, the slider carries a .158 wOBA on the surface but a higher .274 xwOBA, suggesting that production should remain stable but will not maintain its current pace. In relation to his strikeout totals, both of these pitches have generated a sub 19.0% whiff rate, which suggests his strikeout totals will likely remain in the bottom percentile.

In terms of secondaries, Wrobleski mixes in a curveball (7.6% of the time) and a sinker (3.7%) of the time. His curveball has generated a rough .332 xwOBA while his sinker holds a .490 xwOBA, suggesting both pitches are reliable. The curveball has generated whiffs at a low rate of 5.9%.

Overall, Wrobleski sits with a 3.82 xERA, which places him above average but suggests he may face some regression during the campaign. His low 12.0% whiff rate and 9.8% K% do not leave much room for error, given that he cannot miss bats. However, he does have above-average command (5.4% BB%), which should keep his WHIP relatively low.

Despite the low walk rate, over his four outings, Wrobleski has walked at least four batters in two games (zero in the other two), suggesting some volatility in his profile.

Justin Wrobleski dealing 😤🔥

Another stellar outing!

6 innings of scoreless baseball. Had a little trouble early in the first two innings but settled in and took over from there.

Now in line for his 4th win to start the season… Wrobo looking like the Wreal deal 💪⚾️ 🤖

VIA:… pic.twitter.com/2UCfCJP64G

— Dodgers Nation (@DodgersNation) April 26, 2026

The 25-year-old boasts an effective fastball and slider, which should continue to bring his solid results. While he is not the top target for strikeouts, he is a fine SP4/SP5, especially with a positive match on the slate. For those needing a ratio boost, Wrobleski is a top target on the waiver wire.

Nick Martinez, Tampa Bay Rays

15% Rostered

The 35-year-old has spent much of his MLB career bouncing between the bullpen and the starting rotation. However, with the Tampa Bay Rays, Martinez has not only found a role in their rotation but has performed quite well and is enjoying one of the most dominant runs of his lengthy MLB career.

Across five starts (30 innings), the right-hander has posted a 2.10 ERA with a 1.10 WHIP. He has struck out hitters at a modest 16.4% K rate but has shown high-end command, allowing walks at a low 6.6% rate. Unlike Wrobleski above, Martinez throws four pitches more than 10.0% of the time and has thrown at least six total pitches at least 20 times during the season's opening month.

Martinez leans on his sinker, which he threw 32.3% of the time. This pitch has posted a strong .242 wOBA with a low .250 SLG. However, it has been a pure "pitch to contact" option, as it has generated a weak 4.5% whiff rate.

His current No. 2 pitch has been the changeup, which he has thrown 27.3% of the time in the early going. This is his primary whiff pitch, boasting a 35.8% whiff rate and a .136 xwOBA. Last season, this pitch was just as successful (.240 xwOBA, 29.6% whiff rate), but he threw it only 19.8% of the time. Seeing him lean on this pitch should net him far more upside in the strikeout department.

During the early part of the season, this pitch was his No. 1 option, but he has since shifted to his sinker, as shown below. Martinez should continue to lean on both pitches, as they not only play well off each other but also his changeup is the driving force behind his strikeout totals.

In addition to those pitches, Martinez deploys a cutter and four-seamer at a combined 18.5% rate, and mixes in a curve and slider 11.6% of the time. Neither of the four pitches has been overly impressive in terms of contact allowed, but his curveball has been a steady whiff option throughout his career.

Per Baseball Savant, Martinez ranks in the 95th percentile in fastball run value and the 99th percentile in speed, showing how effective his sinker and changeup are. However, his lack of a breaking ball (11th percentile in run value among breaking balls) limits his overall production.

Given his hot start, Martinez is a fine addition as mid-end SP4 when looking for volume and a boost in WHIP. His underlying 4.67 xERA suggests regression is coming, but given that he can limit base runners and hard contact (33.0% hard-hit rate), he should continue to enjoy steady success. If he can continue to expand his company's deployment, his stock price should climb as well.

Martinez projects to have slightly more long-term upside than Wrobleski, as he has shown far more whiff potential.

Foster Griffin, Washington Nationals

30% Rostered

One of the more interesting potential early-season breakouts has been Foster Griffin of the Washington Nationals. Griffin was once a first-round pick with the Royals, but logged 7 2/3 innings with them before heading overseas to pitch for the Yomiuri Giants. With the Giants (over three seasons), Griffin looked quite formidable, holding a 2.46 ERA over 315 2/3 innings.

This strong showing earned him a ticket back to the major league on a one-year "prove-it" $5.5 million deal with the Nationals. Given that the Nationals do not have much depth in their current roster, Griffin has been given an immediate role on Day 1 and has looked the part.

Through 33 2/3 innings of work, the left-hander has posted a 2.67 ERA with a 1.07 WHIP. He has struck out 30 hitters while holding a solid 7.3% BB%. However, Griffin's strikeout upside has been to climb over his last three outings, which makes him even more worthy of a target on the waiver wire.

In his first three starts (15 1/3 innings), Griffin struck out just 12 hitters but carried a 1.76 ERA with a 1.11 WHIP. Over his last three outings, the 30-year-old has racked up 18 punchouts over 18 1/3 innings, holding a 3.44 ERA with a 1.04 WHIP. During these three games, he struck out at least seven hitters in two, and he is coming off his most dominant outing of the season.

On April 26 (facing the White Sox), Griffin logged seven hitless frames with two hits, two walks, and eight strikeouts.

So far, Griffin has deployed an extensive pitch mix, throwing at least five pitches more than 10.0% of the time and seven pitches more than 7.0% of the time, as shown in the visuals below.

In his most recent outing (shown below), Griffin made a slight tweak to this by throwing his sweeper more often, deploying it at 18.0% of the time, which was the driving force behind his surge in strikeouts.

Overall, Griffin has begun to throw his sweeper more often, which explains why his strikeout totals started at one on the lower end, but have gradually increased throughout April, especially over his last three games.

Overall, this pitch has generated an elite 36.7% whiff rate with a .316 xwOBA. His changeup (his No. 4 pitch) has been just as effective, boasting a .193 xwOBA with a 27.3% whiff rate. While he did not throw it as much in his most recent game, he has begun to lean on his changeup more often, as shown below. If he can continue to use this pitch along with his sweeper, Griffin could see his strikeout totals soar.

While the track record is very limited, Griffin has two emerging whiff pitches, which make him an intriguing target on the waiver wire. While his cutter and four-seamer have been far from dominant, the 30-year-old is putting himself into high-end streaming territory.

Kumar Rocker, Texas Rangers

15% Rostered

Rounding out our list, we'll be the top layer with likely the most upside, former top prospect Kumar Rocker. Rocker has shown high-end upside at times during his young career, but has never been able to sustain it. Last summer, Rocker logged a career-high 64 1/3 innings for the Rangers but held a modest 5.74 ERA with a 1.46 WHIP.

This season, Rocker has shown steady development, posting a 3.38 ERA and 1.31 WHIP over 26 2/3 innings. He has struck out 22 hitters while posting an 8.7% BB%. However, his ratios were inflated due to his shaky start to the season. In his first three outings, the former third overall pick logged 14 2/3 innings to the tune of a 4.30 ERA with a 14:7 K:BB.

Over his last two starts, Rocker has logged at least six innings in back-to-back games while holding a 2.25 ERA, 1.08 WHIP, with an 8:3 K:BB. Is this recent urge sustainable or just another flash in the pan for the former top prospect?

As shown below, Rocker has been a primary two-pitch pitcher this season, using his sinker and slider to do most of the heavy lifting. His sinker has been far from effective, carrying a .398 xwOBA with a low 15.5% whiff rate. However, his slider has been the opposite, generating a strong .209 xwOBA with an impressive 29.4% whiff rate.

In his most recent outing (April 26), Rocker made a notable tweak that is worth highlighting. While his sinker has been his clear No. 1 pitch this season, in this lone outing, both pitches were thrown at a similar rate, as shown at the end of this line graph below. Instead, this allowed him to throw his changeup and four-seam more frequently, both of which have netted strong results in the early going.

If Rocker can continue to ease off his sinker and instead allow his slider, changeup, and four-seamer to become reliable pitches, he could eventually find more sustained success in the major leagues.

Given that his track record for fantasy success is very short, managers should not rush to the waiver wire to pick him up. However, for those in the deeper leagues, now is the time to stash him (or acquire him at a much lower FAAB bid) before a potential breakout. If Rocker were to follow a similar trend in his pitch mix in his next outing, his rest-of-season outlook would look far clearer.

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