Starting Pitcher Fantasy Baseball Targets, Avoids - Analyzing BB% and GB% Improvements

While strikeout-minus-walk rate (K-BB%) is widely considered to be among the most crucial pitcher metrics, it's also a good idea to take a look at walk rate (BB%) and ground-ball rate (GB%) to learn more about a starter's skillset. After all, it's helpful to have a pitcher who pounds the strike zone and keeps the ball on the ground.

Pitchers with strong control can limit baserunners, which can help keep their WHIP in check. Those who induce groundballs at a high rate can limit home runs -- having a lower HR/9 is important to maintain a reasonable ERA.

In this article, I took a look at five starting pitchers who were among the biggest improvers in walk rate and ground-ball rate. I used the "Year to Year Changes" section of "Leaderboards" at Baseball Savant for this data. You will be surprised to read some of the names on these two lists, including a particular Marlins pitcher who appears in both.

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Starting Pitcher Improvers in BB% (Walk Rate)

Bryan Woo, Seattle Mariners

I feel the need to share this disgusting Bryan Woo slider I just came across.

If Woo continues to develop the secondaries (and stay healthy), he could easily be SP1 in Seattle pic.twitter.com/n7xgqBhIMh

— Nate Schwartz (@_nateschwartz) February 17, 2025

Bryan Woo trimmed his walk rate by 5.6 percent last season, putting up an impressive 2.8 percent BB% in 121 1/3 innings. One key contributor was likely the improvement of his sweeper, which induced a 41.7 percent whiff rate, an increase of 10.6 percent from the previous season, getting more hitters to chase out of the zone. The only question for Woo is health, but you're likely to get high-quality innings when the 25-year-old righty is on the mound.

VERDICT: Target but make sure to take safer pitchers to mitigate injury risk with Woo.

Jack Flaherty, Detroit Tigers

Jack Flaherty found his control last season, putting up a 5.9 percent BB% (-4.3 percent) en route to a resurgence in Detroit, resulting in a trade to the Dodgers. Now back with the Tigers, Flaherty is in a good spot to build off last season's results, which were aided by one of the best pitching coaches in MLB in Detroit's Chris Fetter.

The main concern with Flaherty is health -- we saw a decline in velocity late in the year. This is why a 3.10 SIERA pitcher is available outside the top-30 pitchers.

VERDICT: Avoid paying up for the peak season -- take him only if he falls past ADP.

Jake Irvin, Washington Nationals

Jake Irvin was able to find the strike zone more often last year, posting a 6.8 percent BB% (-3.4 percent). This is a pitcher who gives up hard contact (9.2 percent barrel) and has a low strikeout rate (20.3 percent K%), so it's even more important for him to limit free passes. The most appealing part about Irvin is his ability to eat innings, coming off 187 2/3 frames in 2024.

I'd only go for Irvin if I needed innings in a 50-round draft and hold.

VERDICT: Only in deep leagues -- desperation streamer in all other formats.

Nick Pivetta, San Diego Padres

Nick Pivetta cut his walk rate from 8.5 percent to 6.1 percent last season. This is helpful because he struggles with home runs, putting up a 1.53 HR/9 for his career. While the move from Boston to San Diego is encouraging, if we take a deeper look, we see that Petco ranked 12th in park factor for homers in a rolling average of the last three seasons, per Baseball Savant (Fenway was 16th).

I still like Pivetta, but there's a good chance that the HR/9 will remain an issue.

VERDICT: Target for strikeout upside, but understand ERA risk due to home run problem.

Starting Pitcher Improvers in GB% (Ground Ball Rate)

Brandon Pfaadt, Arizona Diamondbacks

Brandon Pfaadt induced a lot more grounders last year, bumping his ground-ball rate from 32.6 percent to 42.2 percent. This has a lot to do with the fact that the D-Backs righty threw his sinker 22.2 percent of the time (up from 9.9 percent in 2023). The pitch was much more effective in 2024 (.308 wOBA) compared to 2023 (.398 wOBA).

Having more confidence in a pitch to induce weak contact can help Pfaadt have a breakout season.

VERDICT: Target this underrated innings-eater who deserved better results last season.

Reese Olson, Detroit Tigers

Reese Olson improved his ground-ball rate from 42.1 percent to 52.4 percent last season. There weren't any notable changes in pitch mix for Olson, so perhaps this is just the story of a young pitcher getting better. This is a 25-year-old righty coming off a 3.93 SIERA season.

Injuries limited Olson to 112 1/3 innings last year -- if he can stay healthy in 2025, we could see a true breakout year, making him a terrific late-round target.

VERDICT: Terrific sleeper later in your draft.

Chris Sale, Atlanta Braves

Chris Sale got his ground-ball rate back to career norms at 46.0 percent en route to an NL Cy Young in 2024. This terrific debut season with the Braves has made Sale a third-round pick in 2025 fantasy baseball drafts. I'm not willing to pay that premium for a 35-year-old veteran who has dealt with injuries throughout his career.

In fact, we saw Sale finish off the year with a back issue. With that in mind, I'll let someone else take the risk.

VERDICT: I'd pass on current ADP due to health concerns.

JP Sears, Athletics

JP Sears is an innings eater better suited for 50-round draft and holds, but it's still worth noting that he bumped his ground-ball rate from 30.5 percent to 37.9 percent. This helped Sears keep the ball in the park, trimming his HR/9 from 1.78 to 1.39. However, it's hard to feel confident about that continuing in 2025 with the change in ballpark.

The Athletics will be playing in a much more hitter-friendly park in Sacramento this season.

VERDICT: Not good enough to warrant a roster spot.

Ryan Weathers, Miami Marlins

Ryan Weathers (Miami Marlins)

Weathers gained Velo in 24' from 95.1 MPH vs. 95.6 MPH and had glimpses throughout the year of being an ace.

He has the potential to increase whiffs with his arsenal and also displayed an ability to limit walks (6.5% BB%) and generate GBs (47.6%). pic.twitter.com/7bjRFfEMoQ

— Running From The OPS (@OPS_BASEBALL) February 21, 2025

Here you have it: the one pitcher who was on both top-five lists for BB% and GB% improvers. Ryan Weathers lowered his walk rate from 11.3 percent to 6.7 percent while increasing his ground-ball rate from 37.0 percent to 49.3 percent.

Those significant improvements helped Weathers put up a 3.98 SIERA in 86 2/3 innings. The 25-year-old lefty had his 2024 season shortened by a left index finger strain, but he looks like a terrific sleeper this season, even on a rebuilding Marlins team.

VERDICT: Quickly becoming another one of my favorite sleepers.

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