Strikeout Rate Risers and Fallers for Week 6: Buy or Sell?

Due to a combination of harder throwers and hitters focusing on hitting for power, strikeouts are at an all-time high in baseball. For pitchers, this is an ideal trend. The ability to generate swings and misses is the most important skill to possess, as it's the only true way to control what happens after the pitch is thrown and eliminate the randomness that the ballpark, fielders, weather, and luck can play.

The stat is equally important for fantasy players. Not only are strikeouts a category in every league, but K-rates are often indicative of overall production. A pitcher with a 4.50 ERA with a 25.0 K% may see some positive regression in the future. On the other hand, a hurler with a 3.00 ERA and 16.0 K% may not see the ball continue to bounce their way.

In this column, we'll review two strikeout rate risers and fallers to determine if their performance will improve, hold steady, or worsen as the season moves along.

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Risers

Julio Teheran, Atlanta Braves

2017 K-Rate: 18.6%; 2018 K-Rate: 23.0%; Last 30 Days: 26.5%

In 2017, Julio Teheran was one of the worst starting pitchers in baseball. Among 58 qualified pitchers, he ranked 44th in ERA, 54th in FIP, and 52nd in xFIP. All of those marks were the worst of his career. His struggles could largely be tied to a sudden lack of strikeouts. After tying a career-best in strikeout rate in 2016 (22.0%), Teheran fanned only 18.6% of the batters he faced in 2017, his worst mark as a major-leaguer. Teheran's stock was understandably down coming into 2018, but the start of the season has him trending upward again.

Through his first 37 innings, Teheran has a 3.65 ERA and 35 strikeouts. His swinging-strike rate is currently at a career-high 12.3%, and he's getting more swings outside of the strike zone (32.0% vs. 30.6%). Batters are having a significantly harder time putting the ball in play against him, registering a meager contact rate of 71.6%. That number puts Teheran in the neighborhood of pitchers like Noah Syndergaard, James Paxton, and Charlie Morton.

Teheran's success can be traced back to a resurgence in his slider and changeup. Both pitches had negative values last season after previously being quality offerings for the right-hander. With better horizontal and vertical movement on the pitches this season, he's seeing better success. The slider has registered a swinging-strike rate of 24.0% after dropping to 16.7% last season, and the change is sitting at a healthy 14.6 SwStr% -- more than double his 2017 rate (7.6%).

There are some red flags to note with Teheran. His walk rate is one of the worst among qualified starters (11.8%), and he's throwing the ball in the strike zone only 40.6% of the time, well below his career rate (45.0%). Those numbers need to improve to avoid pitching closer to his peripheral stats (4.92 FIP, 4.67 xFIP), as his batting average on balls in play (.239) and strand rate (82.9%) are unlikely to stay at their current levels. Given Teheran's generally steady control over his career (7.1%), though, the walks figure to decrease as the season wears on. His fastball velocity is also down by two miles per hour, sitting at an average of 89.4. But Teheran is still pitching effectively with the pitch despite its reduced velocity and movement. Of 116 starting pitchers to throw the four-seamer 100 or more times this season, Teheran's xwOBA on the pitch (.299) ranks 20th.

Overall, there's a lot to like about the adjustments Teheran has made in his secondary offerings to get more swings and misses. If that continues and he possesses better control moving forward, he's on the road back to being a solid mid-tier starting pitcher for fantasy players.

Tyson Ross, San Diego Padres

2017 K-Rate: 15.1%; 2018 K-Rate: 27.0%; Last 30 Days: 30.6%

Four years ago, Tyson Ross was a rising star in baseball and earned his first All-Star appearance in 2014. Injuries got the better of him, however, as he pitched only 54 1/3 ineffective innings in 2016 and '17 with the Padres and Rangers. He returned to San Diego on a minor-league contract this season and made the starting rotation out of spring training. Ross brought his pre-2016 form back with him to San Diego, too.

For most baseball fans, the 31-year-old re-emerged onto the scene on April 20, when he took a no-hit bid into the eighth inning against the Diamondbacks and struck out 10. What wasn't clear at the time was whether that was a one-game fluke or if Ross was again a dependable big-league pitcher. In two starts since, he's registered 16 strikeouts in 10 innings. For the year, he's maintaining a 3.28 ERA and 27.0 K% in 35 2/3 innings. That K-rate is higher than even his peak, so that figures to come down. But his start is still worthy of attention.

Although he hasn't regained his pre-injury velocity, Ross has gone back to his former pitch mix. At his peak, the slider was his primary offering, used between 41% and 44% of the time. In 2017 with the Rangers, that number dropped to 32% because the pitch didn't have its former bite. His SwStr% on the slider dropped to 11.8%, leaving the four-seamer, which was his third pitch in 2014 and '15, to become his primary offering. It didn't go well, with hitters crushing it for a .446 xwOBA.

With more time to recover from his surgery for thoracic outlet syndrome, Ross' sharp slider has returned and so has his fondness of throwing it often. The breaking ball has again become his primary offering, currently being used a career-high 47.3% of the time, and is up to a 17.7 SwStr%. That's not quite his 24.0% peak in 2013, but it's well above average.

Ross likely won't maintain a strikeout rate this high all season long unless he gets more whiffs. His 10.3 SwStr% is below league average (10.6%) and his career rate (10.7%). But his slider is back to being a valuable pitch, and as long as he continues keeping his walks in check, Ross should maintain relevance as a fantasy option.

Fallers

Jameson Taillon, Pittsburgh Pirates

2017 K-Rate: 21.3%; 2018 K-Rate: 19.4%; Last 30 Days: 15.6%

The 2018 season couldn't have started off much better for Jameson Taillon. After two starts, he was sitting pretty with a 0.89 ERA and a 32.0 K%. While no one expected Taillon to suddenly become a strikeout artist, there was hope he'd continue to improve in his third full season at the big-league level after raising his K% from 20.3% to 21.3% in his second year. But over his last five starts, the strikeouts have suddenly disappeared. Taillon registered 16 punch-outs in his first two outings and has just 14 since. What happened?

In all likelihood, those were simply outlier games. Whiffs have never been Taillon's forte, with a career 8.2 SwStr% that nearly matches his 2018 rate of 8.3%. Among 94 qualified pitchers, only 16 have a lower rate than that. He certainly has the velocity you'd expect from a high-strikeout pitcher; his four-seam fastball and sinker both average 95 mph. He also does a nice job getting hitters to chase, with his O-Swing% (32.5%) ranking in the top 25% of starting pitchers.

But his off-speed pitches, along with his sinker, are more conducive to getting groundballs than punching hitters out. Taillon's top swing-and-miss offering is the changeup; however, it's his least-used pitch and its SwStr% (12.7%) is nothing special. His curveball, despite its above-average spin rate, has registered just an 11.0 SwStr% for his career.

That's not to say Taillon has no fantasy value, though. His groundball rate is excellent at 55.5%, and he doesn't issue many walks (7.1 BB%, 6.4% for his career). For the most part, he also does a nice job limiting hard contact, which keeps his home run numbers down. Only three pitches have been barreled up by opposing batters this season -- just 2.7% of all batted ball events, which ranks second in the game behind Aaron Nola. But without any dominant pitches, it's hard to see him becoming a strikeout force barring any significant changes. He'll continue to have a nice floor for fantasy owners without any tantalizing upside.

Sonny Gray, New York Yankees

2017 K-Rate: 22.6%; 2018 K-Rate: 18.9%; Last 30 Days: 15.9%

After an injury-filled 2016, Sonny Gray mostly returned to his All-Star form in 2017, becoming one of the most coveted arms at the July trade deadline. The right-hander stayed healthy, limited hard contact and, most encouragingly, missed bats in a way he hadn't since his rookie season in 2013. His strikeout rate was the second-best of his career, and his SwStr% (11.9%) was his best by a wide margin. Expectations were high coming into his first full season as a Yankee. To say he hasn't met them would be an understatement.

Through his first 33 innings, Gray's ERA sits at an ugly 6.00. His strikeouts are down and his walks are way up (13.2 BB%). Gray isn't getting swings and misses the way he did in 2017, nor is he getting hitters to chase at the same rate. Only 9.0% of all swings against him have been whiffs, and his O-Swing% has dropped to by nearly five percentage points to 27.0%. His wildness isn't doing him any favors, as hitters are swinging less against him overall. However, they're making more contact — with more authority and elevation — when they do take the bats off their shoulders. His groundball rate, which ranked 11th in baseball in 2017 (52.8%), is down to 46.7% and hitters are punishing him for an average exit velocity of 90.9 mph, fourth-worst among qualified pitchers

Some changes in pitch repertoire may be playing a part in his struggles. As FanGraphs' Sheryl Ring noted, Gray isn't throwing his fastball-sinker combo nearly as much in 2018. Both pitches have been blasted when he uses them, though that may be because his velocity was down in a few of his starts. He's also throwing his slider far less and focusing on the curveball. That's not a bad thing necessarily: his curveball spin rate ranks 11th among 95 starters who have used the pitch 25 or more times. The bender also has a career-best 16.9 SwStr% against it. But his slider, which has dropped to a 12.9% usage rate, is suffering as a result. It was his best pitch for whiffs in 2017 (22.1 SwStr%), and that number has fallen to 13.9% this year.

Some better batted ball luck should come Gray's way, which will help. He's allowing a .327 BABIP along with a low strand rate of 67.5%. However, the control issues and hard contact will keep those numbers inflated if he doesn't correct them. If he continues to struggle missing bats as well, he'll struggle to reproduce his numbers from last year. He's not in droppable territory for fantasy owners, but he's someone to look at selling if someone offers a trade based on his 2017 output.

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