Miami Marlins Prospect Watch: Spotlight on Sean Guenther

MIAMI, FL - JUNE 25: A detailed view of Marlins Park during the game between the Miami Marlins and the Arizona Diamondbacks at Marlins Park on June 25, 2018 in Miami, Florida. (Photo by Mark Brown/Getty Images)
MIAMI, FL - JUNE 25: A detailed view of Marlins Park during the game between the Miami Marlins and the Arizona Diamondbacks at Marlins Park on June 25, 2018 in Miami, Florida. (Photo by Mark Brown/Getty Images) /

Sean Guenther signed with the Miami Marlins in 2017 for a $198,500 bonus out of Notre Dame. Guenther started in 12-of-66 appearances for the Fighting Irish in three seasons, racking up a 3.51 ERA, a 1.34 WHIP, and 153 strikeouts in 182 innings.

Guenther, who is a 5’11”, 185 lb. left-handed native of Atlanta, GA, is’s current number 363 overall prospect, and the 50th highest rated left-hander in the minors (as of 8/8/18). According to the baseball draft report, he’s got a fastball that peaks at 93 MPH, as well as a good slider, an average curveball, and a changeup. His well-rounded arsenal tempted the Miami Marlins enough to make the call in the seventh round, despite his stature. I’ve written about Guenther before, here.

In 13 games, including 12 starts last season between the Batavia Muckdogs and the GCL Marlins, he was 1-4 with a 3.83 ERA, a 1.18 WHIP, an a .270 oppBA. This season has been trending somewhat worse from a statistical standpoint. He’s was 2-4 with a 5.14 ERA, a .336 oppBA, and a 1.52 WHIP before Monday’s start. Here’s a look at Guenther while with the Fighting Irish:

In Guenther’s last four starts before Monday, he had allowed 34 hits in 17 innings. In the second game of Monday’s doubleheader, he struck out seven in as many scoreless innings, walking zero and allowing two singles. The 85 GameScore was far-and-away the best of Guenther’s minor league career, and may signify that he has this whole “baseball” thing under control. He got 63-of-83 pitches in the strikezone, a 76 percent strike rate.

If Guenther completes this season on a high note, he would be in line to begin next year with the Jupiter Hammerheads. He’s got two more starts to prove himself at the middle-A level. Provided he resumes more-or-less normal progression through the system, he would be in line to join the Miami Marlins in Spring Training in 2020, with a possible chance to break camp with the club in 2021.

Other Top Performances for Miami Marlins Minor Leaguers

Luis Palacios (DSL)

Palacios continues to befuddle opposing hitters in the Dominican Summer League. He pushed his record to 7-0 for the season, with a 0.91 ERA by striking out five in five innings of work. He allowed one run on five hits and a walk. He’s 11-0 over the course of his career with the DSL Marlins, and has four walks versus 58 strikeouts in 59 2/3 innings this season. More on Palacios’ great season here.

Dalvy Rosario (DSL)

As he does on most game-days, Rosario batted in the third spot in the order for the DSL Marlins. He was two-for-three with a single and a double, drawing a walk, stealing two bases, and scoring twice. The DSL Marlins topped the DSL Astros, 4-2. I wrote about Rosario, here.

Connor Scott (GSO)

The Greensboro Grasshoppers played a double-header today, and managed just seven hits in two games despite splitting with the Kannapolis Intimidators. Scott, Miami’s fourth overall prospect, led off the first game and went one-for-three with a walk as the Hoppers fell, 1-0. In game two, Scott hit his first professional home run, leading off the game by giving Greensboro a lead they wouldn’t relinquish. The Hoppers won, 2-0. Scott later added a sacrifice fly, scoring Samuel Castro. Our own Hector Lozada wrote about Scott prior to the draft, here.

George Soriano (GCL)

Soriano pitched the fifth through the ninth innings for the GCL Marlins, holding the GCL Astros scoreless on a walk and two hits. He struck out four, and handed the game to Karl Craigie, who earned the 10th-inning victory. I wrote about Soriano, here.

More from Marlins Prospects

Brandon Miller (GSO)

In Greensboro’s early game, Miller pitched 4 2/3 innings of relief, allowing a run on two hits and a walk. He struck out five and took the hard-luck, 1-0 loss. Michael Napoles wrote about Miller for Marlin Maniac last year.

Brian Schales (JAX)

The Shrimp fell, 3-1 to the Birmingham Barons. Schales was a bright spot, going three-for-four with a solo home run, his 10th of the season for double-A Jacksonville. I wrote about Schales, here.

Jameson McGrane (BAT)

McGrane earned the victory for the Muckdogs in their 10-inning, 1-0 win over the West Virginia Black Bears. He pitched two hitless innings of relief, walking one but striking out four and lowering his ERA to 1.06.

Jordan Yamamoto (GCL)

Yamamoto, Miami’s 16th ranked prospect, started for the GCL Marlins, his second rehab start this pass through. He struck out five in four frames, allowing a run on two hits and no walks. He earned no decision, but is now one step closer to rejoining the Jumbo Shrimp. I touched on Yamamoto for Marlin Maniac, here, and for Fish Stripes, here.

Milton Smith (GCL)

Smith led off for the GCL Marlins as they defeated the GCL Astros on a 3-2, 10-inning walkoff. Smith scored the winning run after going three-for-five with two singles, a double, and his sixth stolen base of the season for GCL.

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