Pitcher Advanced Metrics Studs and Duds - SIERA For Week 26

Welcome back to RotoBaller’s Statcast pitcher Studs and Duds article series! Each week I have selected an advanced stat, chosen two top performers and two under-performers, and analyzed what those stats could mean for future fantasy output. As the season winds down, I'll revisit one of my favorite metrics: SIERA. 

SIERA is a great metric for capturing a pitcher's independent performance. It quantifies a pitcher's performance by trying to eliminate factors the pitcher can't control on their own. Fielding-independent pitching (FIP) is a stat that also attempts to do this, but unlike FIP, SIERA considers balls in play and adjusts for the type of ball in play. The formula can be found here for those who want to get into the nitty gritty. SIERA is a stat I use throughout the season to gain insight into how pitchers are performing relative to how they should be.

At this point in the season, season-long stats likely won't help fantasy managers make their final lineup decisions. That being said, it is never too early to start analyzing how particular players performed this season and what it could mean for them next season. As I have done throughout this series, I will not focus on obvious fantasy studs for this article. Let's take one more look at SIERA this season!

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SIERA Studs

All stats current as of Sunday, September 19, 2021.

Aaron Nola, Philadelphia Phillies

(8-8, 4.48 ERA, 3.20 SIERA)

Aaron Nola is typically a high-end fantasy pitcher, and while he has looked like it at times this season, he has not fit that mold overall. He has posted pedestrian surface numbers so far, particularly his 4.48 ERA. That being said, his 3.20 SIERA is one of baseball's best. Should his stats give fantasy managers cause for concern, or can they expect some positive regression in 2022?

There are several signs that point to better numbers ahead for Nola. First, he has not allowed much contact. His 73.6% mark is in the top-20 in baseball. Also, his 5.2% walk rate is a career best and his 30.3% strikeout rate is stellar. Nola's .307 BABIP is higher than his career .294 mark, but this may not be due solely to bad luck. His batted-ball profile is mediocre overall, but it is one of the worst we've seen from Nola. His 89-MPH average exit velocity and 37.2% hard-hit rate aren't far off from his career 87.8-MPH and 34.6% career averages, but his 14.1-degree launch angle is the highest of his career and is much higher than his 9.6-degree career average. Nola's SIERA suggests that this is nothing to worry about, but I find it difficult to derive such a strong SIERA from his batted-ball profile.

The 28-year-old has some mixed signals under the hood, but he has been a fantasy stud his entire career. His underlying numbers suggest that he got quite unlucky this season, and he was still able to display high-end control while striking a ton of hitters out. His batted-ball profile was at a career low, but his SIERA suggests that it wasn't as bad as it seemed. Taking everything into consideration, I would write this off as an unlucky season for Nola and would trust him once again in 2022.

Yu Darvish, San Diego Padres

(8-10, 4.13 ERA, 3.43 SIERA)

This veteran has been a fantasy staple for many seasons now. Yu Darvish has been a low-WHIP, high-strikeout pitcher throughout his career, and this season has been no different. However, the 35-year-old has posted a mediocre 4.13 ERA on the season with an inflated 6.23 ERA in the second half. His 3.43 SIERA tells a different story, but what should fantasy managers think heading into next season?   

The interesting thing here is that there isn't really anything alarming under the hood for Darvish. His 27.7% K rate and 5.9% walk rate are in line with his season marks, as his 3.54 SIERA. His batted-ball profile has been average this season. His average exit velocity and hard-hit rate are in the 68th and 81st percentiles of baseball, respectively. The thing that does stand out is a 16.7-degree launch angle compared to a 13.8-degree career average. This has led to a poor 2.42 HR/9 metric in the second half of the season. The abundance of home runs doesn't jive with his strong SIERA, leaving fantasy managers in a bit of a conundrum heading into 2022.

This will be a tougher one heading into next season. On the plus side, Darvish has a bunch of strong underlying signs, such as his WHIP, strikeout rate, and SIERA. On the flip side, his ERA has been poor lately and he has given up way too many home runs, despite his SIERA. Darvish will be 36 heading into next season, which always brings concerns of decline. The underlying numbers overall support Darvish, and I would be willing to draft him in points leagues if his value is good. That being said, I would not be comfortable hanging my hat on him as a surefire, higher-end fantasy pitcher.

SIERA Duds

All stats current as of Sunday, September 19, 2021.

Chris Flexen, Seattle Mariners

(12-6, 3.66 ERA, 4.73 SIERA)

This pitcher came out of nowhere this season and has been quite the fantasy surprise. Chris Flexen played the 2020 season in the KBO League but has been an effective starter for the Mariners in 2021, going 12-6 with a 3.66 ERA over 28 starts. He has been a fantasy steal in 2021, and fantasy managers are probably excited for what Flexen can offer next season. However, his 4.73 SIERA, besides being much higher than his ERA, is one of baseball's highest among qualified pitchers. Flexen likely helped fantasy managers get to the postseason, but should he be trusted to do the same next season?    

Flexen's 5.4% walk rate is great, but his 1.26 WHIP is simply mediocre because he has given up so many hits. A look at his batted-ball profile helps explain this, as well as his high SIERA. His 89.7-MPH average exit velocity and 39% hard-hit rate are in the 28th and 47th percentiles of baseball, respectively. His 11-degree launch angle isn't bad, but it isn't low enough with all the hard contact he has allowed. Further, his 83% contact rate is tied for the highest among qualified pitchers. The combination of allowing so much contact and specifically hard contact has led to a .303 BABIP for Flexen, which is actually lower than his .316 career mark. The low ERA and relatively low BABIP despite his batted-ball profile and SIERA suggest to me that Flexen has gotten quite lucky this season.

Flexen is a low-strikeout, high-contact pitcher with a sub-par batted-ball profile and expected stats. Despite that, he has put together a great season for the Mariners and fantasy managers. This one seems pretty straightforward to me. I would be looking to sell-high on Flexen in keeper/dynasty leagues and would avoid him in re-draft leagues next season.

Zack Greinke, Houston Astros

(11-6, 4.11 ERA, 4.59 SIERA)

This final pitcher has had a long career as a solid fantasy pitcher, but things have not been quite so good for Zack Greinke this season. The quirky 37-year-old has posted a lackluster 4.11 ERA over 29 starts and has a 4.59. SIERA to back that up. May it finally be time for fantasy managers to turn away from Greinke at this point in his career?

Greinke has changed his pitching style over time and has never been a hard thrower. This means he needs to locate all of his pitches well, and he has throughout his career. However, this season things have not worked as well. Greinke has left his four-seam fastball in the center of the plate far too often and has also kept his curveball up at times. As such, hitters have taken advantage, leading to a 1.53 HR/9 rate that is much higher than his career 0.95 average. His batted-ball profile has actually been above-average, with an exit velocity and hard-hit rate in the 67th and 80th percentiles, respectively. However with his SIERA so high, it seems that Greinke has to pitch perfectly with his pitch arsenal to be effective.

Greinke has had a great career utilizing what he has to work with, but this season hasn't been quite so good. His peripheral numbers haven't been awful, but his SIERA suggests that Greinke has actually gotten lucky this season. His strikeout rate has never been top-notch, but he saw a big dip this season in addition. This dip, combined with his age, makes me question his potential fantasy value in 2022. I would be willing to draft Greinke towards the end of the draft, but would not want to buy into him as a middle-of-the-rotation fantasy option.

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