Kendall Graveman and the Mariners Bullpen Continue to Exceed Expectations

Kendall Graveman delivers a pitch during the 2020 season/Photo Courtesy of Seattle Mariners on Facebook

Last Wednesday, Seattle Mariners manager Scott Servais walked out to the mound to take the ball from his young-right-hander Justin Dunn. The game was tied at one a piece, and the Orioles were threatening with runners on first and second. Given the leverage of the situation and Seattle’s struggles offensively, Servais went to his best reliever, Kendall Graveman.

After a lineout, wild pitch, and walk, he faced a bases loaded spot. With all 6,504 fans at T-Mobile Park on the edge of their seats, Graveman came set from the stretch, which had become routine for the former starter turned reliver. To Servais’s delight, Graveman delivered a 98-mph sinker with 19 inches of horizontal movement that shattered the bat of Chance Sisco and generated an inning-ending ground out to keep the game tied.

For Graveman, this was his third outing and third different scenario to inherit in the last seven days. He slammed the door on the previous Thursday with a three-out save in Houston, earned a hold on Sunday after a scoreless eighth inning against the Angels, and was entering this ballgame in the sixth. Like he has the entire season, he displayed his versatility, promptly tossing another scoreless frame to keep the game tied and ultimately help Seattle earn their 17th win.

Early Bullpen Success

Without question, the brightest spot for the Mariners this season has been their bullpen. Entering Saturday morning, their 2.68 earned run average was tied for first in baseball. Moreover, their 1.2 fWAR and 3.60 FIP ranked fifth and sixth, respectively.

This has been a pleasant surprise for Mariners fans as many were underwhelmed by the organization’s attempt to strengthen what was one of the worst bullpens in baseball last year. In a reliever market that was headlined by Liam Hendriks, Trevor Rosenthal, Blake Treinen, and Trevor May among others, Seattle was not able to make any head-turning additions. However, it appears that General Manager Jerry Dipoto’s creativity has paid off, as the additions of Keynan Middleton, Rafael Montero, and Will Vest have looked very promising so far.

Of course, like most hot starts, patience is important as bullpen sustainability is difficult to come by. The majority of this bullpen doesn’t have a long track record as many of its arms are either bounce-back candidates or haven’t had strong sample sizes. Additionally, it is important to consider that Seattle’s bullpen currently has MLB’s lowest strikeout rate at 20.9 percent, the fourth lowest soft contact rate at 13.4 percent, and their opponents .239 batting average on balls in play ranks at the bottom of the American League according to FanGraphs. In other words, opponents are putting the ball in play frequently and making solid contact more often than not, which may suggest that some M’s relievers are getting lucky, and their defenders have been well placed.

However, other numbers indicate that the core of the Mariners bullpen’s stats may be sustainable as Keynan Middleton, Kendall Graveman, Drew Steckenrider and Casey Sadler all have above average expected numbers.

PitcherxBAxwOBAHard Hit %Exit VeloBarrel %
League AVG.243.31335.2%88.36.5%
Graveman.183.22920.7%84.73.4%
Middleton.180.30528.6%88.87.1%
Steckenrider.216.27332.3%89.13.2%
Vest.274.33836.4%90.82.3%
Sadler.216.29143.3%87.76.7%
Misiewicz.267.31832.4%88.32.7%
Seattle Mariners Statcast Metrics Compared to MLB Average (as of 5/8)/Data Courtesy of Baseball Savant

The Resurgance of Kendall Graveman

Take what you will with this data, only time will tell what is in store for Seattle’s revamped bullpen. If there is one arm to keep an eye on, it is Kendall Graveman who has rejuvenated his career. After undergoing Tommy John surgery in 2018 and a quick minor-league stint in the Chicago Cubs organization in 2019, Graveman signed a 1.5-million-dollar deal with the Mariners entering the 2020 campaign.

During his first start in the teal and blue, it was apparent that Graveman had improved stuff featuring a fastball and sinker that sat around 95 to 98 mph, which previously hovered around 92 to 95 mph. To put the cherry on top, he struck out the side in his first inning of work, baffling the daunting top of the Astros lineup who had faced the pre-surgery version of him nine times before.

Graveman freezes Jose Altuve with a 98-mph-sinker/Media Courtesy of MLB Advanced Media and the Seattle Mariners

After two starts where Graveman showed signs of fatigue after multiple innings of work, he was placed on the injured list due to a benign bone tumor in his spine. When he returned a month later, he was assigned to strictly pitch out of the pen and showed signs of comfort. In nine relief outings after his return, Graveman allowed four earned runs in 10 innings pitched. In that span, opposing hitters were 6-33 with just two extra-base hits.

Meet Kendall Graveman – The Reliever

This change may have been overdue as Graveman struggled to find success deep in ballgames over the entirety of his career. Opposing hitters are hitting .332 and have an OPS of .895 when facing him for the third time. Moreover, Graveman even struggled with endurance when he was at his best. In 2016, when he posted career highs in strikeouts, innings pitched, and WAR, opponents slashed .328/.369/.505 when facing Graveman for a third time, compared to .249/.300/.380 during the first and second times around. Because relieving does not require him to face a lineup more than once, he was able to throw harder and be more aggressive making the move an excellent fit for the right hander.

In 2021 so far, Graveman has carried over his success as a reliever having not allowed a run in 14.1 innings pitched. In that span he has 16 strikeouts, while allowing just four hits and three walks. The peripherals back up his success as well. Opponents have an average exit velocity of 85 mph against him which sits in the top five percent of the league. Furthermore, hitters have an expected batting average of .181, an expected weighted on-base average (wOBA) of .229 and a hard-hit percentage of 20.7 percent. You guessed it; all those numbers rank at the top of baseball.

For context, during his best season as a starter in 2016, Graveman’s expected ERA was still 5.01 (about a run higher than his non-weighted ERA) and his hard-hit rate, strikeout rate, and average opponents exit velocity all ranked in the bottom 20 percent of the league. This early success as a reliever may suggest that Graveman is on a similar track to other failed starters like Liam Hendriks, Zack Britton, and Andrew Miller.

With the move to the pen, it appears that Graveman has also tightened up his repertoire as he will not need to face any lineup more than once in most outings. He has stopped throwing both his cutter and curveball and has dramatically increased the usage of his slider, a pitch he only threw 10 times last year and has used about seven percent of the time throughout his entire career.

Graveman’s Sinker and its horizontal break on full display last Tuesday against BAL/Courtesy of @PitchingNinja on Twitter

So far this season, he has used it about 23 percent of the time and the adjustment has paid off. Opposing bats are 1-18 against the pitch and it has generated a 54.2 percent whiff rate. Additionally, of all sinkers in MLB, Graveman’s is tied for the third highest run value of -5. This pitch is incredibally effective as it breaks oppisite of his slider, allowing him to create more deception and tunnel his pitches. Apposing hitters also have an expected batting average, slugging percentage, and wOBA under .215 against his sinker, giving him two pitches that would be considered elite if he can maintain these numbers for a larger sample size.

If Graveman sustains this success, it would be logical for Seattle to explore shopping him at the trade deadline in July. He will be a free agent at the conclusion of this season and his salary will be easy for any team to take on.

However, Graveman has been an important piece in the clubhouse as he is currently one of the leaders for a young and inexperienced pitching staff. Seattle was in a similar spot last year when they sent Taijaun Walker, another player who was integral to the team’s culture, to the Blue Jays. Dipoto reportedly was interested in bringing back Walker in 2021 at the time of the trade, but there did not seem to be as much traction during the winter. Nevertheless, in this case the Mariners will likely have more flexibility in their bullpen and payroll that could allow them to bring back Graveman for 2022 in the event that they do trade him.

Of course, it is worth noting that his success as a reliver comes from an incredibly small sample and it will be interesting to watch how the league adjusts to his resurgence as the season goes on. However, with that said, Graveman’s flexibility and success in the Mariners’s bullpen has been essential to Seattle’s ability to stay in ballgames this year. Be sure to keep an eye on him as his season continues to evolve.


According to Baseball Reference, Graveman’s quick start of 14.1 scoreless IP is one of the best to open a season by a Mariners reliever since Kazuhiro Sasaki tossed 20.2 consecutive scoreless innings to open up the 2002 season. In more recent years, Tom Wilhelmsen allowed just one earned run in 22 straight innings to start the 2013 campaign.


Data and satistics courtesy of Baseball Savant, Baseball Reference, and FanGraphs. Last updated at 5/8/21, 2:00 p.m. PT

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