"I'm here, ready to go," Maybin said. "[The rehabilitation] was long. I'm healthy, and that was my biggest objective."
Maybin responded by going 2-for-4 with a double and a run in the Padres' 4-2 win over the Nationals.
The Padres optioned reliever Kevin Quackenbush to Triple-A El Paso to make room for Maybin on the 25-man roster. Quackenbush, who was added Friday, appeared in one game, allowing two runs over 1 2/3 innings in a loss to the Nationals on Friday.
Maybin appeared in 10 games with El Paso since he officially started his Minor League rehab stint on April 11. He started slow but finished with five hits in his final five games, hitting a home run on Tuesday. All told, Maybin hit .243 in 37 at-bats.
Maybin had a higher frequency of harder contact the longer his rehab stint went, but that wasn't the checkpoint he needed to know that he was ready to rejoin the Padres.
"It was just playing games," Maybin said. "It was realizing my body felt good. That was my checkpoint."
Maybin had been in Sacramento with El Paso. And with the Padres heading to San Francisco late Sunday for a three-game series that starts Monday, manager Bud Black was asked why the team wouldn't just have Maybin meet them there.
"We felt we wanted to get him out here and in a game -- every game is important," Black said. "You don't want to put it all on one guy, because they all have got to do it. But Cam can do some things on the baseball field -- he has speed, has some power.
"It's good to have Cam back."
The Padres entered Sunday's game with the fewest runs in the big leagues (65). The Astros, who rank 29th, have scored 15 more runs (80).
Last season, Maybin spent time on the DL with first an impingement to his right wrist, which later required season-ending surgery. Maybin also missed time after he tore the posterior cruciate ligament in his left knee. All told, he played in just 14 games.
Maybin signed a five-year, $25 million contract extension in the spring of 2012. He'll make $5 million this season, $7 million in '15 and $8 million in '16. There's a $9 million club option for '17 that includes a $1 million buyout.