The decision to go with Murphy was difficult, because infielder Donovan Solano, a non-roster invitee, had a sensational camp.
In 22 games, he batted .410 (16-for-39), compared to a .225 average for Murphy, who is 9-for-40.
"We talked to Solano today," manager Ozzie Guillen said. "Solano is staying in Triple-A. We're going to take Murphy. Solano has had the best Spring Training I've ever seen. I had to explain to him everything about the details, and why he's not on the ballclub. It was kind of hard."
Solano will travel with the team to Miami and be in uniform for the exhibitions on Sunday and Monday against the Yankees.
Solano will start off at New Orleans, playing every day.
His situation is similar to Wade LeBlanc being optioned to New Orleans, despite a strong spring.
As for the bullpen, Gaudin has had a strong spring, posting a 1.26 ERA in nine appearances. Gary Glover, another non-roster invitee, will be heading to Triple-A, despite not allowing a run in 10 2/3 innings.
Solano can play shortstop, third base and second base. Guillen noted he is likely to get the first call if there is a need at the big league level.
"He did something we never thought he was going to do," Guillen said. "He opened a lot of people's eyes. Sooner or later, that's the first guy who is coming up.
"I don't think it's fair, because this kid is playing very well, very well. I wish we could take 26, but we can take 25. We thought, as an organization, as a team, the best thing for him and for us is to send him to the Minors and see what happens. Baseball is not won with 25 guys. They have to be ready."
As for Murphy, Guillen said: "This guy has got big league experience. He got to pinch-hit. How we're going to use him, we don't know yet."
On Saturday, the Marlins officially selected the contract of outfielder Austin Kearns, who now makes the team.