Relievers Swinging-Strike Rate Studs and Duds: Week 14

Welcome back to RotoBaller’s pitchers advanced stats and StatCast studs and duds article series! Each week we will select an advanced stat, choose two studs and two duds, and analyze what those stats could mean for future fantasy output. We have spent most of our time focusing on starters throughout the season, so this week we will show some love for relievers. Specifically, we will focus on fantasy-relevant relievers' swinging-strike rates.

Swinging-strike rate is the percentage of pitches a batter sees that they miss. It is not quite as helpful a metric as strikeout rate for fantasy purposes since strikeouts, not missed strikes in general, hold direct fantasy value. That being said, relievers that can avoid contact are more likely to hold fantasy-relevant spots in the bullpen.

I will take a look at four fantasy-relevant relievers for this article. While it would be interesting to look at swinging-strike rate trends across all relievers, only a portion of them matter as fantasy players. Let's take a look at some of them now!

Swinging-Strike Rate Studs 

All stats current as of 7/1/19

Ken Giles - Toronto Blue Jays

(1.29 ERA, 12-13 save opportunities, 21.2% swinging-strike rate)

Our first swinging-strike rate stud had a wild 2018 but has found his focus in 2019. Ken Giles has locked down the Blue Jays' closer job, posting an immaculate 1.29 ERA, 1.04 WHIP, and a career-high swinging-strike rate. What changed from last season to this season and how is Giles getting his strikeout numbers? 

Two things stand out regarding Giles' turnaround. The first is his pitch mix. He has always relied heavily on a fastball-slider combo, but this season, Giles has used his slider more than his fastball (49.6% usage vs 46.7% usage). This has worked out well; his swinging-strike rate on the pitch is an impressive 28.4%, and his batting average on the pitch is a mere .115.

The second factor is his improved control. Giles has had both a better WHIP (1.04 vs 1.21) and SIERA (1.96 vs 2.96) than last season, indicating that he has been hitting his spots and avoiding damaging contact. This has shown itself specifically in Giles' fastball. His batting average against the pitch has improved from .331 to .286, and his swinging-strike rate has nearly doubled from 7.8% to 14%.

Based on the changes Giles has made, it seems that he has overcome some mental hurdles and is tapping into his talent. His stuff is excellent, and his command is there, which seems to have made a big difference. He is a legit strikeout pitcher and should be a valuable fantasy closer for the foreseeable future.

Edwin Diaz - New York Mets

(4.78 ERA, 17-21 save opportunities, 18% swinging-strike rate)

Our second swinging-strike rate stud broke out in a huge way in 2018 and was one of fantasy's hottest names coming into this season. Edwin Diaz looked like one of baseball's top closers for 2019, coming to a newly-stacked Mets team after notching 57 saves in 2018. However, things have not gone the Mets' way or Diaz's. His 4.78 ERA and 1.38 WHIP are both at a career high. That being said, he has notched 17 saves and has an impressive 18% swinging-strike rate. Should fantasy owners be freaking out? 

Diaz presents a mixed bag of stats. First, his ERA is inflated due to three blow-up outings. Of his 34 outings, Diaz has allowed no earned runs in 26 of them, one earned run in five of them, and then one game each of three, four, and five earned runs. Diaz has been mostly effective, but, given the nature of limited innings as a reliever, his blemishes stand out more. Diaz's arsenal has helped him achieve his success. His fastball sits at 97 MPH with an impressive 17.3% swinging-strike rate, and his slider isn't too shabby either with a 21% swinging-strike rate.

On the other hand, Diaz has gotten hit extremely hard this season. His 47.2% hard-hit rate is in the bottom three percent of the league, and his 16.3-degree launch angle does not bode well either. Consequently, his HR/9 rate is at a poor 1.97 and his BABIP is at an inflated .397. His 2.52 SIERA suggests that he has been getting unlucky overall, but I am not quite convinced given how poor his batted-ball profile is.

This is a tough case for fantasy owners. They have to stick it out with Diaz given where they drafted him, he assuredly has the closer's job, and has shown some good signs. However, his peripherals aren't great, and he has been getting hit way too hard for comfort. At this point, owners can only hope that he can continue to get strikeouts while avoiding damaging contact in the second half. 

Swinging-Strike Rate Duds

All stats current as of 7/1/19

Shane Greene - Detroit Tigers

(0.87 ERA, 22-23 save opportunities, 10.9% swinging-strike rate)

Our first swinging-strike rate dud stumbled his way through being a full-time closer in 2018 but seems to have a much better grasp of the task this season. Shane Greene has been solid as the Tigers' closer, converting 22 of 23 save opportunities with a minuscule 0.87 ERA. The one lacking aspect of his game is the strikeouts; Greene has 32 strikeouts in 31 IP and a 10.9% swinging-strike rate, which are low stats for higher-end fantasy relievers. Should this be a concern for fantasy owners?   

Greene does not fit the profile of a typical closer. He does not throw hard; his sinker, his primary pitch (45.5% usage) averages just 92.9 MPH. His secondary pitches are decent swing-and-miss pitches. His swinging-strike rates on his cutter (29% usage) and slider (22.1% usage) sit at 15% and 17.3%. Overall, though, Greene is not an overpowering pitcher.

As such, he mostly pitches to contact (75.6%). The good thing is that he has done a decent job avoiding hard contact (89-MPH average exit velocity, 36.7% hard-hit rate, 12.7-degree launch angle). This batted-ball profile is ok but not great, and his 3.56 SIERA, while still good, is much higher than his current ERA.

Greene has been a mediocre pitcher in his career until this season. Even last season, when he notched 32 saves, he had a poor 5.12 ERA. Greene clearly has the Tigers' closer job on lock and has been getting saves, but his lack of strikeout potential and pitch-to-contact approach at the end of close games makes me nervous. Further, his name has been floated around in trade talks, and there is no guarantee that he would maintain his closer's role with a new team. If I owned him, I would shop him around and try to sell high before the second half of the season begins.

Wade Davis - Colorado Rockies

(5.76 ERA, 12-14 save opportunities, 10.8% swinging-strike rate)

Our second swinging-strike rate dud has had a rocky start to the season (pun completely intended). Wade Davis has posted a massive 5.76 ERA in an injury-shortened season. He has converted 12 of 14 save opportunities but has also posted his lowest swinging-strike rate since 2013. Davis has traditionally been a high-end fantasy option, so should owners be panicking?

Simply put, Davis seems to have been unlucky to this point. To start, his command has been way off (1.76 WHIP compared to 1.26 career, 13.7% walk rate compared to 9.1% career). While this is obviously a cause for concern, the fact that his numbers are so much higher than his career marks makes me believe that bad luck is involved, rather than Davis having completely lost his touch. In alignment with his control problems, Davis' .352 BABIP is much higher than his .286 career point. His drop in swinging-strike rate could also be attributed to his control. Davis' pitches are all similar in terms of velocity and spin rate from the past several seasons, so his arsenal doesn't seem to be the cause of his issues.

Davis has had some poor outings this season but has historically been a great closer. He will be given a long leash by the Rockies and I am inclined to do the same. He still will hold fantasy value as long as he continues to convert save opportunities and it should only be a matter of time before luck starts to turn his way.

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