Biggest Fallers: K-BB%, Part 1

K-BB% is a valuable metric because it shows which pitchers can combine strikeout ability with pinpoint control. Pitchers with high K-BB% possess high floors and ceilings because even when they’re not accumulating strikeouts, they are still usually able to pound the strike zone.

The list below shows pitchers with the highest drop-off in this rate from 2018-2019.

Part 1 of this series will examine five of the biggest K-BB% fallers in 2019, sorted by ADP, beginning with the first five pitchers coming off the board.

Patrick Corbin (LHP, Washington Nationals)

Corbin turned in a strong debut season with the Nationals, posting a 3.25 ERA, 1.18 WHIP, 8.4 BB%, and 28.5 K% in 202.0 IP. His walk rate increased by 2.4% while his strikeout rate decreased by 2.3%, as Corbin threw less first-pitch strikes (2% decline in F-Strike%) and hitters laid off pitches outside of the strike zone (2.2% decline in O-Swing%). Hitters were also able to generate more hard contact off Corbin, as his Barrel% rose from 6.0% to 9.4%.

Despite this decline, Corbin remains a solid pitcher, led by his slider, which is one of the most dominant pitches in the game. Steamer projects Corbin for a 3.57 ERA, 1.23 WHIP, 7.9 BB%, and 27.0 K% in 192.0 IP. It’s likely that his dominant 2018 season was his ceiling, so we can safely project a season similar to last year, perhaps with a slight decline. This makes Corbin more of an SP2/3 type - a risky pick at his current market value. It would be wise to pair Corbin with a safer option, rather than draft him as the ace of your rotation.

Trevor Bauer (RHP, Cincinnati Reds)

Bauer was one of the most disappointing pitchers in baseball last season, with a 4.48 ERA, 1.25 WHIP, 9.0 BB%, and 27.8 K% in 213.0 IP. His season really fell off the rails once he was traded to Cincinnati, where he posted a 6.39 ERA, 1.35 WHIP, 7.7 BB%, and 27.5 K% in 56.1 IP. These numbers were inflated by an unsustainable 1.92 HR/9 and 60.8 LOB%. It’s likely that these struggles were the result of acclimating to a new team and new league. Bauer also tinkered with his pitch usage - his curveball (-6.1%) was used less, despite being one of his better pitches, while his cutter (+5.9%) was thrown more, even though it induced a .324 xwOBA. Hitters were also able to square up his fastball (increased xwOBA from .377 to .401).

The encouraging news is that Bauer still has 94.5 MPH velocity with a strong swinging-strike rate (12.2%). Steamer projects him to put up a 3.93 ERA, 1.25 WHIP, 8.7 BB%, and 28.1 K% in 200.0 IP. With a full offseason in Cincinnati working with a promising coaching staff, Bauer could return to form in 2020 - he’s a great bounce-back candidate this year.

Hyun-Jin Ryu (LHP, Toronto Blue Jays)

Ryu stayed healthy and fantasy owners reaped the rewards, as the Korean lefty put up 2.32 ERA, 1.01 WHIP, 3.3 BB%, and 22.5 K% in 182.2 IP in 2019. However, a move to a home run haven with turf in Toronto is going to affect his numbers. Ryu does a great job suppressing home runs (0.84 HR/9), but playing at the Rogers Centre along with hitter-friendly division rival parks like Yankee Stadium, Camden Yards, and Fenway Park will likely cause regression in this stat. Ryu is a ground-ball pitcher (50.4 GB%) and the turf at Rogers Centre can be unforgiving at times.

The Blue Jays also have one of the weaker infield defenses - sophomores Vladimir Guerrero Jr. and Bo Bichette each had their fair share of struggles. This means that Ryu’s .278 BABIP will likely increase, which will also impact his overall numbers. When you add the injury risk (last season was his first 150+ IP year since 2014), Ryu looks like a player to avoid. Steamer projects Ryu for a 4.26 ERA, 1.26 WHIP, 5.4 BB%, and 21.0 K% in 186.0 IP. You would be wise to opt for a pitcher with more strikeout ability at this stage in your draft.

Masahiro Tanaka (RHP, New York Yankees)

Tanaka had a disappointing 2019 season, posting a 4.45 ERA, 1.24 WHIP, 5.3 BB%, and 19.6 K% in 182.0 IP. His SwStr% fell from 14.1% to 10.7%, primarily due to the decline of his splitter - the pitch declined from a 21.7 SwStr% to a 11.5 SwStr%. While the slider remains a plus pitch (14.7 SwStr%, .257 xwOBA), the decline of the splitter allowed hitters to crush pitches in the zone, as shown by the increase in Z-Contact% from 81.0% to 86.6%. Tanaka underwent surgery to remove a bone spur from his pitching elbow this past October, so perhaps this was something that affected his performance in 2019.

He is entering a contract year in 2020, but he’ll need his splitter to return to form in order to have a better season. Steamer projects a 4.54 ERA, 1.29 WHIP, 5.5 BB%, and 20.6 K% in 180.0 IP. He’s worth a look as a back-end starter since he’s pitching for an elite team in a contract year but temper your expectations. 

Mike Foltynewicz (RHP, Atlanta Braves)

Foltynewicz had a sharp decline in 2019, posting a 4.54 ERA, 1.35 WHIP. 7.5 BB%, and 21.4 K% in 117.0 IP. However, when looking at his season more closely, you start to become more optimistic about his 2020 outlook. Foltynewicz missed the first 25 games of the season due to bone spur in his right elbow. He struggled mightily upon returning, putting up a 6.37 ERA, 1.42 WHIP, 7.7 BB%, 19.2 K% in 59.1 IP - this poor performance got him sent down to the minors to regain some confidence. Once he was recalled to the big leagues, he returned to form, putting up a 2.65 ERA, 1.08 WHIP, 7.4 BB%, and 23.8 K% in his final 57.2 IP.

This stark turn-around seems to indicate that his early-season struggles could be attributed to mechanical issues that are commonly experienced in a return from injury. Steamer projects Foltynewicz to post a 4.73 ERA, 1.35 WHIP, 7.7 BB%, and 21.6 K% in 181.0 IP. This is a conservative projection that Folty should beat fairly easily. Target him in your drafts as a cheap upside pick to fill out your rotation.

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