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7/25/2013 7:32 P.M. ET

Recent hiccups highlight Porter's bullpen concerns

TORONTO -- After watching his bullpen give up critical late-inning home runs in all three games of this week's series against the A's, Astros manager Bo Porter didn't sugarcoat his concern with regard to the ability of his relief pitchers to get key outs.

"It's a major concern," he said.

Entering Thursday, Astros relief pitchers had served up a whopping 61 home runs, which was 20 more homers allowed than the next-highest total in the Major Leagues. The Padres' bullpen had allowed 41. Houston relievers had a league-high 5.03 ERA.

Travis Blackley gave up a game-tying two-run homer to Coco Crisp in the seventh inning Wednesday, Jose Cisnero allowed a tiebreaking two-run home run to Brandon Moss in the eighth inning on Tuesday, and Blackley and Wesley Wright both gave up late homers on Monday when the Astros blew a two-run lead.

"It's a major concern, because the starters are working hard, and I said this about a week ago -- our starters have been a pretty good mainstay in the course of this year, and when you have a lead late in the game, to me it's the most demoralizing loss in baseball," Porter said. "Those guys down there have been made aware they need to do a better job protecting leads, and you need to win the games in which we're in a position to win."

That being said, Porter said he doesn't anticipate any changes in roles for the time being. He said he keeps tabs on who's pitching well at Triple-A Oklahoma City, but said it wouldn't be fair to bring up any names of players who could potentially be called up.

"The guys we have down there are the guys that are there, and they're going to continue to get the opportunities, until we decide we've given enough opportunities and someone else arrives, and they're going to get the opportunities," Porter said. "I'm going to give them the ball and expect them to get the job done."

Astros getting used to regular series in Toronto

TORONTO -- The Astros' trip north of the border for a four-game series against the Blue Jays marks only their second trip to Toronto. Until an Interleague series in 2011, it was the only city in which the Astros had never played. The Blue Jays and Astros will play yearly now as members of the American League.

And plenty has changed since the Astros' last trip to Toronto, May 20-22, 2011. In fact, the only player currently on Houston's roster who appeared in any game in that series two years ago was Brett Wallace, who was traded to the Astros from the Jays in 2010. Wesley Wright was in the Minor Leagues, and Jose Altuve and J.D. Martinez would make their Major League debuts later that season.

"It's crazy," Wallace said. "There's been so much turnover, and new guys coming in, guys getting traded. It's kind of exciting in the same sense. When we were here last time, we were kind of like, in the middle of the pack, and we weren't winning like we wanted to, but we weren't really in full-blown rebuild mode yet.

"It's kind of fun now that we have so many young guys here now who can come in here and play a really talented team and continue to take steps forward."

Wallace, who was drafted by the Jays out of high school in 2005 but didn't sign, spent Spring Training in 2010 with Toronto, which acquired him in a trade with Oakland. He roomed with Blue Jays catcher J.P. Arencibia and still remains close with several players on Toronto's roster.

"They were all great, and it will be fun to see a lot of them," he said.

Astros sign teenage shortstop prospect Amador

TORONTO -- The Astros signed international free-agent shortstop Wilson Amador, a 16-year-old from the same hometown in the Dominican Republic as former Most Valuable Player Miguel Tejada.

Amador, who hits right-handed, was scouted and signed by Astros director of international Oz Ocampo.

"Amador is a premium athlete, and one of the top shortstops in this year's class," Ocampo said. "Our scouts have observed Amador in numerous workout and game situations in the Dominican Republic, Puerto Rico, and Florida since he was 14 years old. Amador projects to have three future plus tools, as he is a 6.4 [second home-to-first] runner with a strong arm and quick fielding actions.

"Defensively, he's nicknamed 'El Gato' [the cat] because of his quick feet, soft hands, and a quick transfer. Offensively, Amador shows the physical tools to hit and has a very aggressive approach. His plus-plus speed and aggressive base running will be offensive weapons in the future."

Due to a pre-existing injury, Amador recently underwent surgery to repair a growth plate fracture in his right elbow. He is expected to miss approximately six months, but should return to full strength in time for the 2014 Dominican Summer League season.

Callups Cosart, Villar enjoying Major League luxuries

TORONTO -- Forget having to share hotel rooms and early wake-up calls for commercial flights. Life in the big leagues means traveling in style. Just ask pitcher Jarred Cosart and shortstop Jonathan Villar, both of whom are on their first Major League road trip.

"It's very different from when we take flights [in the Minor Leagues]," Villar said. "You can relax and go out. You want to stay alone in the hotel, and you can stay in a single [room]. That's very different."

The Astros, of course, travel on charter flights and stay at luxury hotels. There's also a Major League per diem and bellhops who deliver bags to their hotel rooms.

"In Triple-A, it was more like wake-up at 3 a.m. and go the airport and the flight would leave at 6 and you'd have a couple of connectors, then you get to the city and take a nap and go the park," Cosart said. "It's definitely a big change. It's obviously a lot nicer. I see why people don't want to come back [to the Minor Leagues] when they come here. That's all the more reason to work hard."

Players in Triple-A had to pay extra money to have their own hotel rooms, or they could share with a teammate. Each player has his own room in the Majors.

Worth noting

• Astros outfielder Trevor Crowe began his rehab on Thursday with the team's Gulf Coast League affiliate in Kissimmee, Fla. He's been on the disabled list since June 21 with a sprained right shoulder.

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.