Mervis had struggled at the plate for an extended period, while Simon committed three errors in his most recent game.
Prior to Friday’s series opener against the San Francisco Giants, the Miami Marlins are preparing to make a handful of roster moves, most notably designating Matt Mervis and Ronny Simon for assignment, Fish On First can confirm. Their 40-man and active roster spots will go to outfielder Heriberto Hernández and infielder Jack Winkler. The Marlins officially optioned Graham Pauley to Triple-A Jacksonville on Thursday. That paves the way for Dane Myers to be reinstated from the injured list, per sources.
Mervis was acquired in an offseason trade that sent Vidal Bruján over to the Chicago Cubs. He showed early signs of a potential breakout season, slashing .213/.286/.520/.806 with seven home runs and 14 RBI through the end of April, with a stretch from April 1-17 that he slashed .286/.333/.800/1.133.
It all went downhill after that. Mervis had not hit a home run or driven in a run since April 23 as opponents began attacking him with more fastballs. In 42 Marlins games overall, he slashed .175/.254/.383/.637 with a 71 wRC+. He struck out 37.3% of the time.
Simon earned his first career call-up after an excellent start to the season with AAA-Jacksonville. As a Marlin, he played in 19 games and slashed .234/.327/.277/.604 with five RBI and a 73 wRC+. The baseball world became much more familiar with the versatile switch-hitter on Tuesday when he committed three errors and was replaced midway through the game. Simon received widespread support from current and former players after he was seen crying on television.
Like Simon, Heriberto Hernández signed a minor league deal with the Marlins and had history with president of baseball operations Peter Bendix from their days in the Tampa Bay Rays organization. Through 41 Jumbo Shrimp games, he’s slashing .220/.319/.454/.773 with nine home runs, 21 RBI and a 109 wRC+. The only downside—similar to Mervis—is that Hernandez strikes out 35.0% of the time, though he walks 11.7% of the time. Defensively, he has been a left fielder and designated hitter this season.
With Mervis out of the picture, Eric Wagaman will be Miami’s main first baseman. Although Hernández has played 45 career games at first, none of those were above the High-A level. It was reported by Christina De Nicola that catcher Liam Hicks would see some time at first base, so it looks like he’ll back up Wagaman.
Minor league Rule 5 Draft pick Jack Winkler is also set to make his MLB debut. Through 41 games played, he has slashed .275/.331/.423/.754 with five home runs, 19 RBI and a 106 wRC+. He’s split time between third base and shortstop, but has also played first and second. Winkler’s strikeout rate (26.8%) and walk rate (8.3%) are both lower than Hernández.
Ranked second on the Marlins with 0.9 fWAR in 2025, Dane Myers missed the previous 16 games due to a right oblique strain.
The Marlins 40-man roster will remain full once all these moves are finalized.
The Marlins and Giants kick off a three-game set on Friday night. Cal Quantrill will take the mound at 7:10 pm.