As it turns out, his last-place team's nine-game losing streak hurt more than he showed.
Rodriguez, the first Puerto Rican-born manager in major league history, unexpectedly resigned Sunday after less than one year on the job.
Bench coach Brandon Hyde managed the Marlins against the Tampa Bay Rays on Sunday, but the club will begin a search for an interim manager. Potential candidates include Jack McKeon, the Marlins' special assistant to the owner who led Florida to a World Series championship in 2003.
Rodriguez said it was difficult to leave, given the "positive way the organization is moving, a new ballpark next season and the young core of players."
" I can't say enough about the effort that this staff and these players have put into this season," he said. in a statement released by the team. "I could tell that they continued to give 100 percent effort each and every day on the field. I wish this organization and players nothing but success in their futures."
Rodriguez became interim manager June 23 of last year after Fredi Gonzalez was fired. He was given the job permanently five days later.
"It's been extremely frustrating for everyone," Florida president of baseball operations Larry Beinfest said. "I think everyone here knows what is going on - the way we've played, the way we've performed. It's tough on everyone, especially him.
"He communicated with me early this morning that this was something he was thinking about, and when I got to the ballpark we accepted his resignation."
Florida went 46-46 under Rodriguez, who had opened the season as the Marlins' Triple-A manager in New Orleans.
"This was an extremely frustrated, proud man," Beinfest said. "This kind of caught us a little off guard. I know there's been a lot of speculation, everything, but this is not something I thought was going to happen today."
The Marlins fell to 1-17 in June with Saturday's 7-4 loss to the Rays. They were 32-39 and last in the NL East, 12½ games behind the Phillies.
Beinfest said the team would act quickly on an interim manager.
"So we can move ahead with the business of playing baseball and trying to win games," he said. "When you have a change like this, with a popular person, I think it's tough on a lot of people. You just need to go play baseball, and that's first and foremost."
Beinfest informed the players of Rodriguez's decision during a team meeting before Sunday's game.
Rodriguez was at the ballpark and talked with individual players in the manager's office. He didn't speak with reporters.
"It was surprising, I guess, but I think it's more shocking," Marlins infielder Wes Helms said. "Right now, nothing is going right for us. Right now, it's all negative with the Marlins, that's the way it is. It's tough to swallow, it really is. I do know he did everything he could. We didn't do our job as a team."
"I'm sure he had a lot of sleepless night," Helms added. "I can't speak for him. ... I'm sure it was just killing him or he wouldn't have done it. There's only so much you can take mentally and physically in anything in life. I'm just sure he had enough and couldn't do it anymore."
Florida first baseman Gaby Sanchez said the players have to respect the decision.
"It's definitely difficult," Sanchez said. "We have to continue to play hard, go out there and keep fighting. The season is not over. It's just one of those things where we have to move forward."
Tampa Bay manager Joe Maddon believes Rodriguez was thinking about what was best for his team
"He's one of the nicest, most decent men I've met in this game, and it's unfortunate that he has to feel the weight of this whole moment because it's not his fault," Maddon said. "He's worked so hard to get to this point. They were doing so well a couple weeks ago. That's the strange part about it. We just played them down there and they beat us two out of three. They were playing good baseball."
Beinfest did not rule out additional changes.
"When you go the way we've been going, I think everything is on the table," Beinfest said. "I'm probably on he table as well, and rightfully so. It's been a very difficult period and I think when you go through these things you can't rule anything out."