Statcast Pitcher Studs and Duds - Relievers Swinging-Strike Rate for Week 14

Welcome back to RotoBaller’s Statcast pitcher Studs and Duds article series! Each week I will select an advanced stat, choose two top performers and two under-performers, and analyze what those stats could mean for future fantasy output. In week 9, I wrote an article about starting pitchers' swinging-strike rates (SwStr%) and this week I will show some fantasy love to relief pitchers.

SwStr% is the percentage of pitches a hitter sees that they miss. It is not as directly applicable a metric as strikeout rate to fantasy production since strikeouts hold direct fantasy value as opposed to missed strikes in general. However, relievers in particular are most successful when they can miss bats at a high rate. Generally speaking, relievers who can avoid contact find themselves in high-leverage situations more frequently, giving them more fantasy value.

This week I will take a deep look into two relievers with high SwStr% and two with low SwStr% to see what we can expect from them moving forward. An additional useful reliever/closer resource that can always be consulted for the latest news is RotoBaller's Fantasy Baseball Depth Charts. As I have mentioned in previous articles, I will not focus on obvious fantasy studs, but will choose to analyze more under-the-radar or less-obvious players to give readers the most useful insight. Let's find how these relievers will fare in terms of missing bats for the rest of the season!

SwStr% Studs

All stats current as of Sunday, June 27.

Raisel Iglesias, Los Angeles Angels

(3.86 ERA, 13-16 Save Opportunities, 21.5% SwStr%)

Our first pitcher has been a higher-end fantasy closer for most of his career and joined a new team to anchor their bullpen in 2021. Raisel Iglesias hasn't been the sharpest closer this season, but he has been the Halos' go-to reliever throughout the season and has converted most of his save opportunities. What has been impressive is his career-high 21.5% SwStr%, a value that puts him first among qualified relievers. Can Iglesias continue to convert for fantasy managers or could he be a sell-high candidate? 

The main thing that stands out to me regarding Iglesias' strong SwStr% is his pitch mix. Iglesias has traditionally relied primarily on a four-seam fastball, followed by a slider and then a changeup. However, this season he has thrown his changeup more frequently (28.8% usage vs. 20.8% usage in 2020) than his slider (28.2% usage vs. 33.2% usage in 2020). His slider has historically been a strong swing-and-miss pitch (19.9%) and has been this season as well (26.2%), but his changeup has always been a bit more effective (21.7% in career; 29% in 2021). Iglesias has also benefitted from a career-high 15.1% SwStr% on his four-seamer. His velocity and spin rate are similar to what they have been in the past, but he has done a better job keeping the pitch out of the middle of the plate and working in the top of the zone.

The other positive thing to be found under the hood is that Iglesias' overall numbers can be broken out into two clear time frames. Maybe he just needed some time to adjust to his new team, but Iglesias had a poor first month of the season, compiling a 6.00 ERA with two blown saves and a 21.1% SwStr%. He's looked completely different from May on, posting a stellar 3.22 ERA with a single blown save and a 21.7% SwStr%. The two encouraging things here are that he looks to have settled in and that he was missing bats even when he wasn't pitching well.

Iglesias' numbers may look somewhat lackluster on the surface, but he has the right things going for him. He has been missing bats with all three of his main pitches and has adjusted his pitch mix to build on that. Further, he has started pitching to the level fantasy managers have come to expect and seems to be a lock as the Angels' closer barring a complete breakdown. I see no reason why he should not continue to be one of fantasy's top closers for the rest of the season.

Diego Castillo, Tampa Bay Rays

(3.38 ERA, 12-14 Save Opportunities, 16.8% SwStr%)

Our second pitcher is one who fantasy managers may have shied away from at the beginning of the season given the team he is on. The Tampa Bay Rays have been one of baseball's pioneers in terms of utilizing their pitching staff in new and different ways, so the possibility of a closer committee is never out of the question. However, Diego Castillo has emerged as the team's leading reliever in terms of saves, converting 12 of 14 opportunities with a 3.38 ERA and a strong 16.8% SwStr%. Six relievers in the Rays bullpen have seen save opportunities so far this season, so Castillo will have to continue to pitch well to keep his role. Can his SwStr% continue to be sustainable? 

Castillo is more or less a two-pitch reliever, with his main pitch being his slider at 70.6% usage. The interesting thing is that Castillo manages so many swings and misses with essentially one pitch. He has a great SwStr% rate with his slider at 21.5%, compared to a mere 6.7% with his sinker. His SwStr% and location of his slider indicates that it is a good pitch, but I am a bit surprised that hitters aren't more ready for it given how frequently Castillo throws it.

Even more interesting is how successful Castillo has been with his slider given its lack of movement. The pitch has two fewer inches of relative drop compared to league average (-6%) and 1.8 fewer inches of relative break (-49%). The key to success appears to be Castillo's spin direction on the pitch. He has generated a ton of different looks with the singular pitch type, which essentially gives it the properties of multiple pitches. This appears to be the only explanation for how Castillo has managed to keep hitters so off-balance with the pitch. 

Castillo has generated a strong SwStr% this season by relying heavily on his slider. The pitch doesn't move much, but comes to the plate with numerous spin directions, giving it increased deception. He has pitched well this season and has done so throughout his career, so nothing stands out as a blatant red flag. However, I am still a bit hesitant to bet on a reliever who relies so heavily on a single pitch, particularly a pitcher in a bullpen who could easily sway to a committee. This one may fall to the fantasy manager's personal preference, but I would try shopping around Castillo to see who I could potentially get in return.

SwStr% Duds

All stats current as of Sunday, June 27.

Tyler Rogers, San Francisco Giants

(1.40 ERA, 9-13 Save Opportunities, 13 Holds, 6.4% SwStr%)

When you think of high-leverage relievers, you typically think of hard throwers with at least one biting breaking pitch. What you do not think of is a side-arm/underhand pitcher with an 82.3-MPH rising fastball. The Giants have just such a pitcher in a closer committee in their bullpen this season. Tyler Rogers is an unusual choice for a high-leverage reliever but he has pitched very well this season, converting nine of 13 save opportunities with 13 holds and a minuscule 1.40 ERA. The only aspect of his game that is visibly lacking is his SwStr%, which is second-lowest among qualified relievers. Can Rogers continue to generate fantasy value given his unorthodox pitching approach and uncertain bullpen situation?

The analysis here is fairly straightforward due to Rogers' unique pitching mechanics. His pitching style generates a great batted-ball profile with a two-degree launch angle and an average exit velocity and hard-hit rate in the top-six percent of baseball. However, his stuff cannot overpower hitters so he pitches to contact. His contact rate is the highest among qualified relievers. Again, this may seem like an odd choice for a potential closer, but the fact of the matter is that Rogers is a solid pitcher who can end games and keep runs off the board in high-leverage situations. He has been splitting save opportunities with Jake McGee lately, but often sees hold opportunities when not serving as the closer.

Rogers is a case of a pitch-to-contact reliever who holds fantasy value, particularly in save/hold roto leagues. It is true that he does not strike out many hitters and it is also true that he does not have a firm grasp on the closer role for the Giants. However, the team and he have played so well that he is a valuable fantasy bullpen arm in deeper roto leagues. His lack of strikeouts does limit his value in points leagues to a degree, but I think Rogers will be a worthwhile arm to have throughout the season.

Brad Hand, Washington Nationals

(2.61 ERA, 16-18 Save Opportunities, 7.8% SwStr%)

Our final pitcher has served as a higher-end closer for a variety of teams over the course of his career and is now doing the same with the Nationals. Brad Hand has pitched well with his new team, converting 16 of 18 save opportunities with a 2.61 ERA. He has never been a huge swing-and-miss pitcher, but his 7.8% SwStr% is a good deal lower from his career 10.0% career mark and his 22.9% strikeout rate is much lower than his 33.7% from last season. Are these drops something fantasy managers should be worried about?

The main culprit here is Hand's slider, which is his primary pitch. He implements a three-pitch arsenal with his slider as the primary option (45% usage), followed by a four-seam fastball (39.8% usage), and a sinker (14.8% usage). He has seen a jump in SwStr% for both of his fastballs compared to last season, but his slider SwStr% has dropped from 15.1% in 2020 to 7.5%. Digging deeper, his velocity and spin rate on the pitch is almost identical to what it was in 2020. Further, his spin direction on the pitch has remained similar.

The only visible difference is that Hand has actually gotten more movement on his slider in 2021 than in 2020. He averaged 44.3 inches of drop and 15.9 inches of break in 2020, but has gotten 45.8 inches of drop and 17.3 inches of break in 2021. He hasn't been able to bury the pitch in the bottom corner of the strike zone as well this season, but has still kept the pitch low and out of the middle of the plate.

This odd contradiction spells future regression to me. Hand has gotten strong peripheral results and has thrown his slider in a similar manner to last season. The fact that his SwStr% on the pitch has been almost halved seems like an oddity to me, and I would expect it to tick up towards last season's mark. I don't think there is anything to worry about with Hand here.

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