Injuries to Kodai Senga and Tylor Megill Have Put the Mets Rotation on the Spot

A week ago, as Sean Manaea and Frankie Montas continued their rehab assignments, reporters and fans wondered how the two hurlers — both of whom suffered injuries before the calendar flipped to March — would fit into a rotation that has been one of the majors’ best thus far. “Usually it plays itself out,” responded Mets manager Carlos Mendoza when asked about it. “We still are at least two weeks away from making those decisions and I’m hoping that by the time we get there it is going to be a difficult decision. That means everyone’s healthy. That means everybody continues to throw the ball well and we have some good problems.”

While the Mets still share the NL’s best record (45-28) thanks to the work of that rotation — which has been unusually durable since the start of the regular season — their decision regarding that pair has become more complicated. In rapid succession, both Kodai Senga and Tylor Megill have landed on the injured list, the former with a hamstring strain and the latter with an elbow sprain. Each is likely to miss at least a month, and so far, neither Manaea nor Montas has shown he’s ready.

On Thursday at Citi Field, Senga absolutely carved up the Nationals, holding them to one hit — a first-inning single by James Wood — and one walk while striking out five. With one out in the sixth, he ran to cover first base after inducing CJ Abrams to hit a sharp grounder to Pete Alonso, whose throw to the pitcher was high. Senga leapt in the air to catch the ball, then extended his right leg far enough for his toe to touch the corner of the bag in time to beat Abrams. It was an impressive, acrobatic play, but the pitcher immediately grabbed his right hamstring upon landing, then tumbled to the ground.

The Mets placed Senga on the 15-day injured list on Friday afternoon and sent him for an MRI, which yielded comparatively good news, in that the 32-year-old righty suffered only a Grade 1 strain. The Mets have shut him down for two weeks, after which doctors will reevaluate him. If he’s fully healed, he’ll still have to go through a throwing progression and a rehab stint before he can return to the rotation.

“It depends on the player,” said Mendoza on Friday. “It’s two weeks of very little physical activity. Hopefully we keep the arm going, but he’s got to be symptom-free before we start ramping him up. So could be four, five, six [weeks]. Who knows? But again, it’s a low grade, which is good news.”

This is Senga’s second season in a row landing on the IL. Last year, he strained his shoulder capsule during spring training, then returned to make one start on July 26, during which he strained his left calf. He didn’t return to the Mets until the playoffs, when he made two starts and one relief appearance totaling five innings. He was decidedly rusty, walking seven, striking out four, and allowing seven runs.

Senga has rebounded from that lost season in impressive fashion, though he hasn’t been quite as dominant as his NL-best 1.47 ERA suggests. His 10.6% walk rate is the third highest in the league among qualified starters — a distinction Senga will shed once the Mets play their next game — while his 23.9% strikeout rate is middle-of-the-pack, 5.2 percentage points lower than his rate in 2023, his first season stateside. Only his homer rate (0.49 per nine, third in the NL) is exceptional. Among starters in both leagues, he’s outperformed his FIP by the second-largest margin:

So how has Senga done it? Kiri Oler recently explored Senga’s reliance upon seam-shifted wake to deceive and surprise hitters with his broad assortment of pitches; he throws six of them at least 5% of the time, with his forkball and slider the standouts. His mixing and matching has helped him remain effective when facing batters a second and third time in a game; his .220 wOBA allowed in the latter situation is eighth lowest in the majors. I’ll add that his ERA-FIP differential owes a lot to sequencing and his effectiveness with runners on base. His 17% double play rate is ninth among qualifiers:

Meanwhile, Senga’s .197 wOBA allowed with runners in scoring position (.103/.224/.172) is the majors’ third-lowest mark among starters; teammate Clay Holmes (.172 wOBA) has the lowest.

As for Megill, the 29-year-old righty experienced what he described as “some pulling” in his elbow during Saturday’s start against the Rays, mainly while throwing breaking pitches, and he particularly struggled to control his slider. Following an MRI, he’s been diagnosed with an elbow sprain, and while the Mets haven’t revealed which ligament was damaged, it’s the ulnar collateral ligament according to Under the Knife’s Will Carroll: “What we have here, per sources, is a very small sprain and one the team thinks they can control and monitor. He’s likely already been hit with some biologics, as is standard with injuries like this, and after about 10 days of rest and treatment, he can begin a quick ramp.” Mendoza told reporters the best-case scenario for Megill’s return is four to five weeks; the worst case, given the involvement of the UCL, is Tommy John surgery.

It’s been an uneven season for Megill, whose 29.2% strikeout rate and 3.95 ERA are both the highest among the Mets’ regular starters. He posted a 1.03 ERA over his first five starts totaling 24 2/3 innings — including the team’s Opening Day game against the Astros — but he has been lit for a 5.56 ERA over his last nine turns, totaling 43 2/3 innings. Even though he’s walked 10.8% of hitters, he has the highest strikeout-walk differential of any Mets starter (18.4%), and his 3.36 FIP trails only Senga and Peterson (3.07, along with a 2.60 ERA). Because he tends to pitch into deep counts, Megill has been kept on a short leash. He’s lasted at least six innings just twice, has just one quality start, and has been pulled from five out of his 14 starts before completing five innings, including a 4 2/3-inning, 10-strikeout effort on May 21 against the Red Sox. He’s one of two Mets to make at least 10 starts while averaging less than five innings per turn, along with Griffin Canning:

Despite that short work, Megill does a good enough job missing bats and barrels to be useful at the back of the rotation.

As a unit, the Mets rotation owns the lowest ERA (2.95) and home run rate (0.74 per nine) in the majors, as well as the NL’s third-lowest FIP (3.55), an impressive showing given the team ranked 19th in our preseason Positional Power Rankings once Manaea and Montas went down, the former with an oblique strain and the latter with a high-grade lat strain. The team is one of just four to have five starters each make at least 13 starts, along with the Angels, Cardinals, and Rays. Peterson, whom Michael Baumann recently wrote about, hasn’t allowed more than three earned runs in any of his 14 starts. He leads the team in innings (86 2/3), quality starts (nine), and WAR (2.0). After backing last Wednesday’s shutout of the Nationals with a seven-inning, three-run start against the Braves on Tuesday night, his 2.60 ERA is fourth in the NL. Holmes, who hadn’t started a major league game since 2018 before signing a three-year, $38 million deal this past winter, has pitched to a 2.87 ERA (11th in the league) and 3.93 FIP. Canning, a former first-round pick who rarely lived up to expectations with the Angels, has so far put up career-best numbers in both ERA (3.80) and FIP (4.19) despite his limited workload.

As for Manaea and Montas, both have scuffled during their rehab assignments. The 33-year-old Manaea, who signed a three-year, $75 million deal with the Mets after delivering a 3.47 ERA and 3.83 FIP in 181 2/3 innings, has made three starts so far, all for High-A Brooklyn. He’s built up from 36 pitches to 46 to 56, but he’s surrendered seven earned runs in 6 2/3 innings. Nonetheless, he’s heading to Triple-A Syracuse to continue his rehab work with a start on Friday. The math of building up pitch counts suggest he probably needs at least a couple more turns before the Mets call upon him.

The 32-year-old Montas, who signed a two-year, $34 million deal with the Mets after posting a 4.84 ERA and 4.71 FIP in 150 2/3 innings for the Reds and Brewers, has been knocked around to an even greater degree. In two starts for Brooklyn and three for Syracuse totaling 13 2/3 innings, he’s got a 13.17 ERA and has allowed seven homers while walking nine and striking out 10. His three Triple-A starts have been particularly bad. He gave up four homers (and five runs) in four innings on June 3, then after throwing an unsightly 76 pitches in 3 2/3 innings on June 8, he lasted only 53 pitches on June 13 while being peppered for seven hits and eight runs and recording just five outs.

As Mendoza said on Tuesday, Montas has been falling behind hitters and “not moving well mechanically on the mound as he’s going through the delivery.” His mechanics reportedly looked better in his between-starts bullpen session at Citi Field, but he’s running out of time. He’ll start for Syracuse on Wednesday but hit the 30-day mark — the maximum-length rehab assignment for a pitcher unless he’s returning from Tommy John surgery or pulled back due to an additional injury or setback — on June 22, before his next turn comes around. The Mets could squeeze in an appearance on short rest before adding him to the 26-man roster, which might be good preparation if they plan to send him to the bullpen.

Until Montas and Manaea are ready, the team does have other options. Paul Blackburn has been slotted into the rotation in place of Senga and will start against the Braves on Wednesday. The 31-year-old righty was limited to 14 starts last year with the A’s and Mets due to a stress reaction in his right foot, a hand contusion and, during the postseason, a spinal fluid leak; when he was available, he posted a 4.66 ERA and 4.63 FIP in 75 1/3 innings. The injury bug bit him again during spring training, and he missed the first two months of this season due to inflammation in his right knee. He threw five scoreless innings in his season debut against the Dodgers on June 2 and has since made two relief appearances, including a four-inning save in a June 8 blowout against the Rockies.

Since neither Manaea nor Montas is likely to be in fighting shape before Megill’s slot comes up on Friday against the Phillies, the team will need a spot starter, with the choice likely to come down to two pitchers at Syracuse who are on the 40-man roster, Justin Hagenman and Blade Tidwell (yes, Blade). Hagenman, a 28-year-old righty our of Penn State, threw 3 1/3 innings in his major league debut on April 16, a bulk appearance following opener Huascar Brazobán. Though his overall 6.15 ERA and 5.15 FIP at Syracuse are ugly, he’s posted a 3.18 ERA with 22 strikeouts and just two walks in 17 innings since returning from a finger injury in mid-May. Tidwell, a 24-year-old righty, was the team’s second-round pick in 2022 out of the University of Tennessee and grades out as a 45-FV prospect. He was cuffed for six runs and nine hits in 3 2/3 innings in his debut on May 4 and at Syracuse has pitched to a 4.76 ERA and 4.28 FIP.

One way or another, Mendoza and the front office will sort out who takes the ball for the Mets. But what seemed like a nice problem to have just a week ago now verges on a cautionary tale. As ever, you can’t have too much pitching.