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2/22/2014 2:25 P.M. ET

Porter to begin implementing replay during spring

KISSIMMEE, Fla. -- Astros manager Bo Porter plans to simulate the use of instant replay as much as he can during Grapefruit League games, even though he won't always have access to a replay monitor. For Porter, it's about identifying potential plays to challenge and learning the terminology and what he can or can't do.

Officials from Major League Baseball, led by Joe Torre and Tony La Russa, briefed the Astros, Nationals, Tigers and Braves during a two-hour, 45-minute meeting Friday on expanded instant replay that will begin this year.

"They did a tremendous job of putting the information together and kind of giving us scenarios," Porter said. "It was long, but it was very much needed, and I think it was very beneficial at the same time."

Porter said one of the issues that was addressed during the meeting was the timing of when you can challenge.

"There were some questions that came up, 'OK, if you have to make it before a pitching change is being made, if that guy leaves the bullpen when does that constitute him being in the game?'" Porter said. "We were able to kind of clarify all of those issues and I think everybody left there yesterday feeling comfortable with the rules, and it's a thing we're actually going to be able to put into practice this spring."

Torre said each team will have at least five games during Spring Training during which it can implement replay, but the Astros are going to have their own program and use walkie-talkies to communicate with their video staff when they're able this spring.

"We're going to go ahead and start from Day 1 and implement our process among myself, [bench coach Dave Trembley], the coaching staff, the video people, so we can practice it the entire spring," Porter said.

Many prospects to report early to mini-camp

KISSIMMEE, Fla. -- Several of the club's top prospects are scheduled to report to Osceola County Stadium on Sunday in advance of a mini-camp that will begin Monday. The group will work out each afternoon until the full Minor League workouts begin in early March.

Among the pitchers participating in the camp are right-handers Travis Ballew, Michael Feliz, Lance McCullers Jr., Brady Rodgers, Andrew Thurman, Vincent Velasquez and Kyle Weiland. The position players include catchers Brian Holberton and Roberto Pena, infielders Nolan Fontana, Tony Kemp, Chan Moon and Rio Ruiz and outfielders Teoscar Hernandez and Brett Phillips.

Astros director of player development Quinton McCracken said the camp will feature some of the top arms in the organization, some players should who could fill in on the Major League side and pitchers who could be headed to a full-season club for the first time so they can get stretched out and get a jump start of learning throwing programs and working with new stuff.

"We've had a third of the guys show up already," he said. "It's been a nice surprise to have guys eager to get the season underway."

The mini-campers, unlike last year, will play five to seven games against other teams.

The full Minor League Spring Training begins for pitchers and catchers when they work out for the first time on March 3. Position players will work out beginning March 7.

Astros focus on defense after early rain

KISSIMMEE, Fla. -- The Astros had to alter their schedule Saturday because of early-morning rain showers, with the pitchers throwing live batting practice first to make sure they got their work in before more rain fell. Position players took batting practice and then worked in a large group focusing on defensive drills.

"We had some weather early on, so we wanted to make sure our pitchers that were scheduled to throw live, we wanted to keep them on schedule," manager Bo Porter said. "We were able to get that in, and it turned into a defensive day from that point on."

Porter said the defense needs improvement, which meant the players weren't able to give each other the post-workout "Astros win!" handshake.

"We didn't execute, and that's why we actually [turned it] into a day of execution from the defensive side of it," Porter said. "We all understand the game of baseball. It's about runs being scored, and I'm a firm believer that the best offense is a good defense. We have to defend the baseball."

That's more than about just making the throws or fielding cleanly, Porter said.

"We've explained this to our guys, from a defensive standpoint it's not just the physical aspect of making the plays," Porter said. "There are a lot of mental things that go into positioning, situations, understanding what to do, what not to do, given the situation. We're going to put our guys in as many of those situations as possible throughout the course of the spring to try to emphasize the importance of these decisions based on situations."

Odds and ends

• Hall of Fame pitcher Nolan Ryan, who was named the Astros executive advisor two weeks ago, will arrive in camp on March 10. As part of his duties, Ryan will work with Astros owner Jim Crane, president Reid Ryan and general manager Jeff Luhnow.

• The Astros will play an intrasquad game Sunday against a curveball machine, with the losing team serving the winning team lunch and banana splits. An intrasquad game against live pitching will be held Thursday, one day before the Grapefruit League opener.

• Crane was scheduled to arrived in Kissimmee, Fla., and be in camp Saturday, but morning rains kept him away.

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.