MACK - Top 28 Prospects - # - 8LHSP - Zach Thornton

 

The excitement about the Mets' prospect pipeline has been building year over year as the team improves their domestic and international scouting.  Many of the Mets' picks are being discussed throughout baseball, so Mack has boiled it down to the top 28 to give the readers a glimpse into the team's future.  This series will run for 28 days, counting down from #28 to #1.  

The entire list can be viewed by clicking "2026 Top 28 Prospects" on the top menu bar.

8.    Jack Thornton

LHSP        6-3        170        24/yrs in July

5th round pick 2023 – Grand Canyon U. (Guess Where?)

2025 – A+/AA:   14-ST, 6-2, 1.98, 0.81, 72.2-IP, 78-K, 11-BB

GROK -

Zach Thornton is a highly regarded left-handed starting pitcher in the New York Mets' minor league system.

At 23 years old (born January 17, 2002, in Winona, Minnesota), he's emerging as one of the organization's most promising arms, particularly noted for his elite command, control, and ability to dominate lineups without elite velocity.

Standing at 6'3" and 170 pounds, Thornton profiles as a potential back-of-the-rotation starter at the MLB level, with scouts praising his deceptive delivery.

Thornton grew up in Lawrence, Kansas, and honed his skills in summer collegiate leagues before transferring to Grand Canyon University (NCAA Division I) for his junior year in 2023. At Grand Canyon, he earned All-WAC second-team honors as a starter, posting a 3.87 ERA over 88.1 innings with 91 strikeouts and just 18 walks—showcasing the command that would define his pro career.

The Mets selected him in the fifth round (159th overall) of the 2023 MLB Draft, signing him for $350,000. Prior to the draft, Thornton had a decorated JUCO career at Barton Community College, where he was named first-team all-conference, conference Pitcher of the Year runner-up, first-team all-region, and third-team All-American as a sophomore in 2022. He also pitched in the Appalachian League (Elizabethton River Riders) and MLB Draft League (Mahoning Valley Scrappers), boosting his stock with scouts.

Thornton's pro debut in 2023 was solid but unremarkable: he split time between the Florida Complex League Mets and Single-A St. Lucie, going 1-1 with a 4.50 ERA in 22 innings.

The real breakout came in 2025, where he dominated across High-A Brooklyn (South Atlantic League) and Double-A Binghamton (Eastern League).

Overall Stats (as of injury in August 2025): 8-2 record, 1.53 ERA, 0.89 WHIP, 24.4% K-BB% rate (16th-best among minor leaguers with 12+ starts), and a sub-2.00 FIP. He ranked among the top 16 minor league pitchers with an ERA under 2.00.

High-A Brooklyn (April-May): 3-0, 0.44 ERA in four starts (20.2 IP), with 24 strikeouts and just 2 walks. Earned South Atlantic League Pitcher of the Month for April.

Double-A Binghamton (May-August): 5-2, 2.13 ERA, including gems like 6.2 IP of one-run ball (8 K's, no walks) and a career-high 7 IP shutout (3 H, 6 K, 0 BB). Named Eastern League Pitcher of the Week for May 19-25.

His 2025 season quietly placed him among the Mets' top pitching prospects, behind headliners like Jonah Tong and Brandon Sproat but ahead of many in raw effectiveness.

Thornton's arsenal isn't built on velocity but on deception, location, and sequencing. His delivery—described as "all movement"—creates late life on his pitches, leading to high whiff rates despite modest speeds. He commands all four offerings well, rarely exceeding 90 pitches per start.

Fastball - Four-seam with significant induced vertical break (16.1 inches) and spin rates of 2,200-2,400 RPM for deception. Sits low-90s, tops out at 93-94 mph. Primary pitch (50-60% usage); plays up due to arm action and command. Generates swings-and-misses despite average velo.

Slider - Mid-80s sweeper with sharp horizontal break; his go-to out pitch against righties.  25-30% usage; above-average command allows him to bury it low-and-away. Complements fastball well.

Curveball - 12-6 breaker for depth and change of pace; used to steal strikes early in counts. 10-15% usage; effective for tunneling with fastball-slider.

Changeup - Fading action to jam lefties; developing but inconsistent. 5-10% usage; more of a show-me pitch, but improving

Cutter (emerging) - Hard horizontal slice added in 2025 for variety against contact hitters. Low usage (~5%); helps shorten plate appearances and set up other pitches.

Scouts note his fastball-slider combo as plus, with the full mix giving him a "crafty lefty" profile similar to a young Jamie Moyer but with better strikeout upside. Areas for growth: Adding velocity (he's young and projectable) and refining the changeup for same-handed matchups.

Outlook - Thornton embodies the Mets' emphasis on polished college arms under David Stearns. If he stays healthy, he's on track for a big-league debut by 2027, potentially as a reliable No. 4-5 starter.

Mack – this is another of those great Mets minor league starters that get little press, due to the emphasis on The Three Amigos (McLean, Tong, Sproat). Don’t be surprised if he sneaks into the open day 2027 roation as an SP4-5.

 

11-6-2025

Tom Brennan/MM

18. LHP Zach Thornton

He pitched great as a lefty in AA, until he badly strained his left oblique a la Manaea, and the LEFTY’S season abruptly ended in late June.  His numbers to that point were dazzling: 6-2, 1.98, 78 Ks in 72 IP, and an 0.81 WHIP.  WOW!  I would have him higher, but let’s see how he returns from his injury in 2026 first.  Yes, Gus, he is a quality lefty.  Great control, can hit 95, but more of a Viola type crafty lefty.  One To Watch In 2026.

 

11-7-2025

Just Baseball

https://www.justbaseball.com/prospects/new-york-mets-top-15-prospects/  

Zach Thornton – LHP – (Double-A): Another Mets pitching prospect who took a leap in 2025, Thornton was drafted in the fifth round in 2023, turning in a decent first pro season before dominating to a 1.98 ERA in 72 2/3 innings at High-A and Double-A in 2025.

A pitchability southpaw, Thornton fills up the strike zone with his low 90s fastball that generates above average carry and extension. His slider is his best swing and miss pitch to both lefties and righties while mixing in a cutter, sinker and curveball as well.

Thornton’s breakout was cut short due to an oblique injury, but he is a high probability depth arm who could potentially miss enough bats to round out a rotation.

 

12-5-2025

Angry Mike/MM

ZACH THORNTON -> Breakout 2026 season has not gone unnoticed by Mets brass, ticketed to hit AAA early.

-> #Mets bullpen requires a complete overhaul, Thornton has the best command in the system, dominated RHB & LHB, & if we want to make a deep post-season run, we need at least 1-2 more reliable arms for the bullpen. Thornton would be perfect, while he waits for a rotation spot to open up for 2027.

 

12-11-2025

Angry Mike/MM

The Mets drafted Zach Thornton in the 5th round of the 2023 draft, and after a solid professional debut, they decided to challenge the young left-hander during the 2024 season. Thornton was credited for putting in a tremendous amount of hard work during the off-season, which is why he enjoyed a breakout 2025 season, posting numbers as dominant as any other pitcher in the system. 

If it wasn’t for an abdominal injury that forced him to miss the final month and half of the season, there is reason to believe Thornton would have not only finished the year in Syracuse, he might have even earned a couple starts at the MLB level.

Thornton is primed for a huge 2026 and will continue to be one of the more closely watched prospects in our farm system by the “House of Angry Mike”, because of the potential upside he offers and for the fact he has the rare potential to continue improving his future ceiling like our other Top Prospects.

 

12-20-2025 –

MACK/MM

Zach Thornton – a particular favorite of mine, my fandom had to take a pause when he went down last season when, on July7th, he suffered a “mild” oblique injury. Have you ever had one of them? Well, there is nothing mild about any level of them. 

Now, try to imagine having that and having to come off the rubber 80-100 times every five days? No, Zach was shut down for the remainder of the season, which prevented him from ending the season in AAA-Syracuse. I have him returning to AA-Binghamton and following the same path that Watson will be on. Two members of the next Three Amigos.

 

1-13-2026

Angry Mike/MM             @AngryMike24

<->  Mets Zach Thornton -> Prior to IL Stint: Hi-A & AA:

-> 10 / 14 Outings went 5+ IP

-> 9 / 10 Outings of 5+ IP allowed 2 ER or fewer

72.2 IP | 16 ER | 78 K | 11 BB | 48 H | 1.98 ERA | 0.81 WHIP

->  29% K-RATE  |  4.0% BB-RATE