NEW YORK -- Fernando Abad threw four innings of one-run ball against the Mets on Saturday, and, in turn, earned himself a permanent role in the Astros' rotation moving forward.

"He's going to be in our rotation," interim manager Tony DeFrancesco said. "What you saw yesterday, four quality innings kept us in the game. I'm really excited about his aggressiveness, and I hope you see a difference from when he was here before as a reliever."

In his first Major League start, Abad allowed four hits and walked four, but he did an excellent job limiting damage with runners on base.

Abad made 30 relief appearances for the Astros before he was optioned to Triple-A in July with a 3.86 ERA. He made three relief appearances for Oklahoma City before he was added to the team's starting rotation, and was called up to make his first Major League start on Saturday after scheduled starter Armando Galarraga was designated for assignment on Wednesday.

Despite Abad's transition from a left-handed specialist to a member of the Astros' rotation, DeFrancesco said he has no worries about the left-hander's durability, citing that Abad was used as a starter during two seasons in the Dominican Winter League. The biggest concern, he said, lies in Abad's pitch selection.

"When you're a lefty situational guy, you're throwing a lot of breaking balls. You're probably a two-pitch pitcher, you're going to throw a fastball, a breaking ball, maybe a slider for a strikeout," DeFrancesco said. "But when you're a starter, you've got four quality pitches and you can mix them in."

Snyder back catching Harrell against Mets

NEW YORK -- Chris Snyder was back behind the plate for Lucas Harrell's start on Sunday against the Mets. With the exception of Tuesday's 7-0 loss to the Cardinals -- Jason Castro got the start -- Snyder has caught every one of Harrell's outings since April 28.

"They feel good working together; sometimes maybe that's a winning combination," interim manager Tony DeFrancesco said. "When you look around, there's some guys who catch knuckleballers better, there's some guys who catch veterans better, but we're just going to go out right now and try to get the best matchups that we can day in and day out."

Harrell struggled on Tuesday, surrendering six runs over five innings in his first time working with Castro since his fourth start of the year.

"Pitchers sometimes need a little bit of extra help, and whatever we can do to get Lucas on track, we'll do whatever we can," DeFrancesco said.

Catching for Harrell has given Snyder a consistent work schedule this season, which was not guaranteed when he signed this winter. Snyder was given a one-year deal (with a mutual option for 2013) in January -- one month after Castro underwent surgery to remove a bone in his left foot that ultimately forced him to miss part of Spring Training.

As a result, the two have formed a nice tandem behind the plate for the Astros, the veteran Snyder serving as a mentor to the 25-year old Castro.

"I think they're feeding off each other," DeFrancesco said. "Snyder does a great job leading. It seems like Castro's been around here a while, but his Major League playing time has been shortened by some of his injuries. But we're trying to get him back there, understanding our pitching staff and leading."

Worth noting

• The Astros announced on Sunday that Galarraga cleared waivers and opted for free agency. Houston designated Galarraga for assignment on Wednesday.

• Justin Maxwell, who has missed five consecutive games with a bruised right index finger, is scheduled to see a doctor in Houston on Monday. DeFrancesco said the team will decide on Wednesday whether to place him on the disabled list.