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8/18/2013 5:12 P.M. ET

Chapman fitting right in since joining Astros 'pen

ANAHEIM -- Rookie left-hander Kevin Chapman is off to a nice start since he was added to the Astros bullpen on Aug. 9 after spending his entire season at Triple-A Oklahoma City.

Chapman had appeared in six games entering Sunday and had allowed two runs -- both unearned -- and only one hit in 3 1/3 innings. What's more, he had faced one batter in four of those six outings, including the first two games of the series against the Angels when he retired Josh Hamilton.

"It's always nice to have some experience, and I have four or five outings now," he said. "It feels like it's just normal, everyday work now and just come in and be ready every day to go into some key situations and get some outs."

Chapman, acquired along with outfielder D'Andre Toney from the Royals in exchange for Humberto Quintero and Jason Bourgeois in March 2012, is one of 12 Astros pitchers to make his Major League debut this year. He was 1-2 with a 3.20 ERA and 61 strikeouts in 50 2/3 innings at Oklahoma City.

"He's done a tremendous job since he's been here," Astros manager Bo Porter said. "He's gotten some big outs for us and in situations you bring him in you have the matchup you want, left on left. Even the other day in Oakland, we got the left-on-left matchup we wanted and we let him face [Yoenis] Cespedes, and he was able to face him and the next lefty. He's done a great job."

Porter credits umpires for right call on tag play

ANAHEIM -- Astros manager Bo Porter conceded Sunday the umpires did what they could to make sure they got the right call during a controversial play in the ninth inning of Saturday's extra-inning loss to the Angels.

The game was tied at 5 in the ninth when Astros outfielder L.J. Hoes was called safe at second base with a leadoff double despite Angels shortstop Erick Aybar tagging him out. Second-base umpire Eric Cooper ruled Hoes safe, but the umpires huddled and overturned the call.

Porter argued at length with Cooper and first-base umpire Jeff Kellogg and said after the game he had not seen the replay, which clearly showed Aybar tagging Hoes.

"They got it right," Porter said. "It's unfortunate for us, but I'm all for getting things right in baseball. It's unusual to see that happen, but I guess you could say the consolation prize is at the end of the day the umpires did get it right."

Porter said last week he was a proponent of expanded instant-replay use in baseball because it would be used to ultimately get the calls correct. But Porter said it was the first time he had ever seen umpires overturn a safe-out call after the umpires huddled.

"I've seen umpires out of position for one reason or another and they rely on the other guys on the crew," Porter said. "But [Cooper] was in position and for whatever reason, his view got obstructed. I'm a complete advocate for getting calls right, and in the heat of the moment you want your guys to be safe and put your team in the best position to be successful and have a chance to win. After going to look at the replay, you have to give those guys credit. They got it right."

Villar sits against lefty to rest ailing thumb

ANAHEIM -- Astros shortstop Jonathan Villar remains hampered by a sprained left thumb he incurred trying to steal third base Aug. 6 against the Red Sox in Houston. Manager Bo Porter said Villar jammed the finger during one of his at-bats Saturday.

The thumb bothers Villar enough the Astros don't want him to swing the bat right-handed, which meant he was on the bench Sunday when Houston faced Angels left-hander Jason Vargas. Marwin Gonzalez made his first start at shortstop since being recalled Wednesday.

"We're going to go ahead and take the precaution," Porter said.

Meanwhile, second baseman Jose Altuve started at designated hitter. He's not quite over the soreness in his left quadriceps muscle, so Jake Elmore started at second base Sunday. The Astros are off Thursday and can give Altuve another day of rest.

"He's been doing much better and [we] want to continue to monitor him," Porter said.

Astros acquire pair of Mexican League stars

ANAHEIM -- The Astros have agreed to terms with the Diablos Rojos (Mexico City Red Devils) of the Mexican League to acquire first baseman Japhet Amador and outfielder Leo Heras. Amador will be assigned to Triple A-Oklahoma City, and Heras will report to Double-A Corpus Christi.

Both players are expected to report to their affiliates within the next week.

"Finding and acquiring the best Mexican talent is a priority for us," said Astros general manager Jeff Luhnow, who was born in Mexico. "We have increased our scouting of the Mexican baseball leagues and believe there are many players that can help the Houston Astros in the future."

Amador, 26, hit .368 with 22 doubles, 36 home runs, 121 RBIs and a .419 on-base percentage in 104 games for the Diablos Rojos this season. The 6-foot-4 first baseman led the Mexican League in RBIs, while ranking second in homers and third in total bases (277). Amador has played in the Mexican League for seven seasons (2007-13) and owns a career .330 average with 112 home runs and 400 RBIs in 503 career games.

"Japhet's numbers speak for themselves," Luhnow said. "Power like his is not easy to find, and we are excited about seeing how his power numbers translate to Triple-A and how he fares against top notch pitching."

Heras, 23, hit .310 with 19 doubles, nine triples, 11 homers, 42 RBIs, 14 stolen bases and a .398 on-base percentage in 91 games for the Diablos Rojos in 2013. The left-handed-hitting Heras, who batted primarily leadoff this season, was tied for second in the Mexican League in triples. Heras made his debut in the Mexican League in 2007 and has compiled a .318 career average with 109 doubles and 89 stolen bases in his seven professional seasons.

"Leo is one of the bright young Mexican stars," Luhnow said. "He has already put together several outstanding seasons at a young age and is ready for the challenge of higher level pro ball in the United States."

Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.