Strikeout Rate Risers and Fallers - Buy or Sell for Week 15

Connelly Doan identifies pitchers whose impressive and underwhelming strikeout rates could make them worth adding or dropping in fantasy baseball for Week 15.

Welcome back to the strikeout rate risers and fallers series for Week 15! Each week we will take a look at two K% risers and two fallers, analyze what is behind those changes, and then decide if they are actionable. A pitcher can best control their fate by generating swings and misses, so this exercise holds particular importance for fantasy value. Understanding strikeout trends and the stats behind them can help you sort through all the noise and determine which pitchers are legit and which pitchers should be avoided.

The players in this article were chosen using RotoBaller’s K% Risers and Fallers premium Tool. This tool identifies players who are surging and falling in strikeout percentage over the last 30 days. The goal of this tool is to help you find pitchers who are showing improving or declining K%.

We are heading into the All-Star Break, so now is the time to make those pivotal roster moves to prepare for the second half. Hopefully, this article can help you out with your rotation moves!

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Strikeout Rate Risers

All stats current as of Sunday, July 7

Shane Bieber - Cleveland Indians

Season K%: 31.5%, Last 30 Days: 33.6%

Our first K rate riser has baffled me all season long, putting up excellent numbers despite sending mixed signals. Shane Bieber has a stellar 3.45 ERA, 1.01 WHIP, and 31.5% strikeout rate this season. That last metric has jumped to a ridiculous 33.6% in the last 30 days. How has he found such success this season?

Let's rehash Bieber's situation once again. Firstly, his pitch arsenal in itself isn't impressive; his fastball sits at 93.2 MPH with average spin and his slider and curveball don't have a ton on spin on them. Despite this, he has managed to rack up strikeouts al season long. His command has been strong as evidenced by his WHIP, but that alone does not explain why his K rate has been so high.

Regarding his K rate spike over the last 30 days, Bieber has simply taken advantage of some favorable matchups. His strikeout numbers for his last six starts are as follows: four against the Yankees, 12 at the Tigers, eight at the Rangers, six against the Royals, 11 at the Orioles, and eight at the Reds. All of these matchups were favorable except the Yankees and Bieber had his lowest strikeout total against them. This isn't to take away from his other performances, but a run of matchups of that quality would help a pitcher look good.

I still can't figure Bieber out, but it doesn't matter at this point. He has been an immense fantasy value and fantasy owners should be able to ride him to solid numbers in the second half of the season.

Chris Archer - Pittsburgh Pirates

Season K%: 25.3%, Last 30 Days: 30.1%

Our second K rate riser has been a disappointment fantasy-wise over the past several seasons. Chris Archer has been a reliable workhorse with high strikeout upside but has also shown a lack of command and an average ERA. He has even been unstartable at times this season with a 5.49 ERA and 1.47 WHIP. The one thing that has been there for him has been the strikeouts, especially over the past 30 days. Is there any hope left for Archer as a fantasy option? 

To answer the previous question concisely, not really. Archer's numbers over his past six starts mirror his season stats. His 30.1% K rate has been impressive, but his 5.23 ERA and 1.48 WHIP have not been. His SIERA over those starts was 4.08, which is considerably better than his ERA. This is the only other sign of hope for him beside the strikeouts; A 30% K rate with a 4.00 ERA is a decent fantasy option, but any K rate with a 5.25 ERA is not.

There isn't a ton to analyze here for Archer. He has gotten hit hard all season (88.7-MPH average exit velocity, 42.4% hard-hit rate), but his SIERA over his last six starts indicates that he has done a relatively better job at limiting hard contact. Simply put, Archer needs to command the zone better to see better overall results. If he can't then it won't matter how many batters he strikes out, he won't be a viable fantasy option in the second half of the season.

Strikeout Rate Fallers

All stats current as of Sunday, July 7

James Paxton - New York Yankees

Season K%: 27.6%, Last 30 Days: 18.5%

Our first K rate faller made this list last week and is leading the pack this week. James Paxton has a mediocre 4.09 ERA and 1.45 WHIP over 70 1/3 IP (he missed most of May with a knee injury). The strikeout rate has been there overall but the command has not been, and Paxton's strikeout rate has suffered over the last 30 days. Paxton is a big fantasy name so it is worth taking another look at him this week.

There is one main factor in Paxton’s game that could explain his drop in strikeout rate and overall performance. The big thing has continued to be Paxton's lack of command. In his past six starts, he has three in which he got seven, seven, and eleven strikeouts per game with a combined four walks and five earned runs. He also has three in which he had seven total strikeouts with eight walks and 13 earned runs. It is not surprising that Paxton has failed to post strikeouts when his command has been off and he has been inconsistent all season long.

Further, the Big Maple's batted-ball profile reflects a lack of command. He has gotten hit hard (39.4% hard-hit rate, 89-MPH average exit velocity, 17.7-degree launch angle), which does not bode well in the small confines of Yankee Stadium. His .358 BABIP is higher than his .306 career mark, but his 4.20 SIERA supports this.

Overall, Paxton has underperformed this season and his underlying numbers support that. His strikeout numbers have been good, but that stat alone is not worth what has come with his lack of control. At this point, fantasy owners can only hope that Paxton can regain his control.

J.A. Happ - New York Yankees

Season K%: 18.9%, Last 30 Days: 14%

Our second K rate faller is a teammate of Paxton; he has been a strikeout pitcher the past two seasons, but his K rate is down this season. 36-year-old J.A. Happ has posted a poor 5.02 ERA with an 18.9% K rate this season (his lowest since 2010) and that mark has fallen even further in the past 30 days. Should fantasy owners have any hope for him?  

Unfortunately for those who own him, the most straightforward explanation seems to be that age is starting to catch up to Happ. His velocity is down this season on his three primary pitches: fastball (average velocity of 91.5 MPH compared to 92.3 in 2018), sinker (89 MPH vs 90.4 MPH), and slider (84.4 MPH vs 85.3 MPH). This seems to have affected his slider in particular as a swing-and-miss pitch, as his swinging-strike rate has fallen from 11.9% in 2018 to 7%.

Happ's last five starts have reflected his performance all season long. He had some tough matchups (Rays on the road and at home and Astros at home) but was unable to take advantage of starts against the White Sox and Blue Jays on the road. His 5.47 ERA over that period won't cut it, and, unfortunately,  his 5.31 SIERA supports his performance.

Happ hasn't been up to his standard of the past several seasons and really hasn't provided much fantasy value. His age, combined with his hitter-friendly home stadium does not bode well for him for the rest of the season.

K-Rate Risers and Fallers - Premium Tool

Identifying top strikeout rate risers and fallers for each week can help you spot the best pickups before your competition. RotoBaller's Premium K-Rate Risers and Fallers tool has you covered every day. As thoughtful fantasy baseball players, we won't lead you astray. This tool will soon be active once we have a large enough sample size in the season to be considered reliable.

This type of data is available as part of our Premium MLB Subscription. Don't settle for basic stats and surface-level advice from other sites. RotoBaller brings you advanced statistics and professional analysis that you need to win your fantasy leagues and DFS games, because we're ballers just like you. We are your secret weapon!

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