Strikeout Rate Risers and Fallers - Buy or Sell for Week 4

Welcome back to the pitching strikeout rate risers and fallers article series! 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.

To this point, I have done one article comparing starters’ 2018 K% to their 2019 numbers and one for relievers. Now that close to a month of baseball is in the books, this week I will take a look at two pitchers with top K%’s and two with low K%'s and assess whether these numbers will continue.

Starting next week, we will have access to RotoBaller’s K% Risers and Fallers premium Tool for further analysis. Until then, let’s take a look at some K%’s and give them a Buy or Sell rating!

Top Strikeout Rates

All stats current as of Sunday, April 21

Greg Holland - Arizona Diamondbacks

48% K Rate

Our first pitcher was a fantasy staple for several seasons, took a dive last season, and seems to be returning to form in 2019. Greg Holland was a top closer with the Royals and Rockies before having an overall poor 2018 with the Cardinals and Nationals, posting a 4.66 ERA with a 22.2% K rate (the lowest of his career). Now serving as the Diamondbacks closer, Holland has already notched four saves with a pristine 0.00 ERA and a 48 K%. Can fantasy players trust Holland after how he performed in 2018?

The first thing to note is that Holland’s start to 2019 isn’t as surprising of a bounceback as it may seem, given that his 2018 wasn’t as bad as it looks. Holland signed with the Cardinals on Opening Day and pitched a mere nine days later. He had no Spring Training to prepare and posted an abysmal 7.92 ERA with a poor 16.7% K rate over 25 innings pitched. However, after joining the Nationals and getting some work under his belt, Holland returned to form with a stellar 0.87 ERA and a 31.3% K rate that resembled his career mark of 31.6% over 21 ⅓ IP. The point here is that Holland only pitched an uncharacteristic first half of last season before correcting himself, so his start to 2019 is not surprising, especially given that he got a full Spring Training’s worth of work.

Holland’s 2019 stats under the hood are extremely impressive; his hard-hit rate, K%, and xwOBA are all in the top 2% of baseball. However, both his whiff rate (31.7%) and swinging-strike rate (14%) are not far off from his career marks of 33.3% and 14.8%, respectively. His pitch arsenal is also similar to 2018 and his average fastball velocity of 92.4 MPH is not the mid-to-upper 90’s it used to be back in the day. This gives me the suspicion that, beyond the fact that a 48% K rate is unsustainable in general, Holland’s K% will decline towards his career average as he logs more than seven IP.

Overall, I think that Holland’s advanced metrics support the notion that he will be a highly valuable fantasy reliever this season. He will not be this fantastic for the rest of the season by the simple normalization of numbers due to sample size. That being said, there is no reason to think that he cannot put up similar numbers to those of the past, which would be a big win for fantasy owners. I am whole-heartedly buying into him.

Caleb Smith - Miami Marlins

33.3% K Rate

Our second top K% pitcher showed some intriguing fantasy signs in 2018 before getting hurt. 27-year-old Caleb Smith showed a proclivity for strikeouts (27%), but was inconsistent overall in 2018, posting a 4.19 ERA and a 10.1% walk rate in 77 ⅓ IP. 2019 seems to be all positive so far for Smith, as he has a tidy 2.35 ERA with an improved 33.3% K rate in 23 IP. Has Smith maintained the strong aspects of his game while ditching the inconsistencies?

Smith has shown some interesting changes in his arsenal from 2018 to 2019 that may help explain his bump in K%. His fastball velocity is just about identical to 2018 at 92.8 MPH. However, his spin rate on the pitch is up (2464 revolutions per minute vs 2365 in 2018), giving the pitch a greater perceived rising motion. His slider has gained significant velocity (84.1 MPH vs 81.6 in 2018); consequently, his K% on the pitch has jumped from 36.5% to 45.5%. Finally, his changeup has slightly less velocity (83.3 MPH vs 84 in 2018) but has an increased spin rate of 1961 revolutions per minute vs 1826 in 2018. These changes are all good signs in terms of Smith maintaining an increased K%.

It looks like Smith’s K% potential is legit, but what about the inconsistent aspects of his game? Unfortunately, it looks like things have not really changed in those departments. His average launch angle is too high at 19 degrees, and while his K% is up, his pitch locations on his fastball and changeup leave something to be desired. His 0.87 WHIP is also a good deal lower than his 1.24 career mark, so it would not be surprising to see some negative regression in that department as well.

The takeaway for Smith is a little unclear at this point. His K% is a legit fantasy tool, but the lack of changes in other aspects of his game make me nervous that he can continue to execute at his current level. I would consider him to be a short-term buy for now or possibly a sell-high target to a competitor who is ready to pay up for what he has done to this point.

Special Mention: Matthew Boyd - Detroit Tigers

36% K Rate

Matthew Boyd has received a lot of attention from the RotoBaller crew (myself included), so I won’t go into too much analysis on him. The 28-year-old has gotten off to a great start to the season, posting a 2.96 ERA, a 1.11 WHIP, and an impressive 36% K rate.

His 2.83 SIERA and 16.1% swinging-strike rate support his strong peripherals, although his career swinging-strike rate is just 10%, so some strikeout regression can be expected. Further, his 18-degree launch angle and 30.4% hard-hit rate do not jive with the fact that he has only allowed a single home run. I’m not ready to buy into Boyd yet, but he should be added if he’s available (he’s currently 78% owned) in case he proves to be the real deal.

Bottom Strikeout Rates

All stats current as of Sunday, April 21

Jake Arrieta - Philadelphia Phillies

16.4% K Rate

This pitcher used to be a flamethrower and a major fantasy asset but posted a pedestrian 3.96 ERA with his lowest K% in five seasons in 2018. Jake Arrieta had a lackluster first season with the Phillies in 2018, and while his 2019 season has gotten off to a strong start overall (3-1, 2.25 ERA, 1.11 WHIP in 28 IP), his K% sits at a mere 16.4%, the lowest since his rookie season in 2010. Will he be able to continue to provide fantasy value with such a low K%?

The 33-year-old’s K% has been on the decline since 2014, so what adjustments has he been making? For one, he has ditched the straight fastball in favor of a sinker exclusively, his main fastball pitch. This looks to be a good move so far; Arrieta’s batting average on his fastball in 2018 was a bloated .400, but the batting average on his sinker in 2019 is a stellar .157. He has also switched up his main arsenal to a duo of sinker and changeup (a classic strategy to keep hitters off balance) over the power slider. This tactic seems to be working for Arrieta overall; he is definitely pitching to contact (83.7% contact rate), but he is keeping the ball the ball down in the zone and balls in play on the ground (8.8-degree average launch angle). He has been pitching more carefully but effectively. One note of caution; Arrieta’s SIERA is currently an ugly 5.23, indicating that his performance has not been nearly as strong at it has appeared.

My verdict here is that Arrieta has definitively changed his pitching style and will not be piling up strikeouts like he used to. However, I am buying that he will be able to succeed as a contact pitcher this season based on the stats, despite his SIERA. He should be able to help fantasy owners in a similar manner to Kyle Hendricks.

Nathan Eovaldi - Boston Red Sox

17.2% K Rate

This pitcher created a massive buzz around his 2018 postseason performance and gained a huge fantasy following heading into the 2019 season. I mean, who wouldn’t be pumped up about a guy who throws in the high 90’s? Unfortunately, Nathan Eovaldi has not continued his success to this point in 2019. The 29-year-old has a 6.00 ERA, a 1.52 WHIP, and a mere 17.2% K rate through 21 IP. Should fantasy owners start to panic after jumping on the bandwagon?

The main thing to note here is that Eovaldi has never been more than an average pitcher in his career with the exception of the 2018 season, especially the postseason. His career 4.21 ERA and 1.35 WHIP are not fantastic fantasy numbers, and while he has always thrown hard, he has never had high strikeout numbers (career 17.6% K rate). His command has been all over the place, leading to an 11.8% walk rate that is a good deal higher than his career mark of 7.3%. His 5.34 SIERA suggests that he has pitched slightly better than his ERA indicates, but not nearly to the level that fantasy owners had hoped.

It is easy for fantasy players to get caught up in small sample sizes, especially when the performance in that sample size is so impressive. This seems to be what happened for Eovaldi; he has been a middling pitcher over the course of his career and there is no new evidence to suggest otherwise. He has never been a strikeout pitcher and is hhindered from pitching in one of baseball’s toughest divisions. I am selling on Eovaldi, although, frankly, I never really bought into him.

Special Mention: Chris Sale - Boston Red Sox

Another pitcher who has received a lot of attention early on has been Chris Sale. The fantasy ace has gotten off to a dreadful start, posting an 8.50 ERA with a lowly 16.7% K rate vs a career 30%. The main issue here is Sale’s fastball velocity, which sits at an average of 92.4 MPH compared to 95.2 last season.

His health is a concern, but Sale topped out at 97.5 MPH in his last start, so he may have just needed more time to get loosened up. I would not panic about Sale; a fantasy player of his caliber deserves a longer leash. He is certainly a buy-low candidate from any owners who are worried about him.

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!

More 2019 Fantasy Baseball Advice