KISSIMMEE, Fla. –- Brad Ausmus had been gone from the Astros for more than a year when catcher Jason Castro made his Major League debut in 2010, leaving the former first-round Draft pick without the luxury of having a veteran catcher to lean on.

The Astros had a huge void behind the plate following the departure of Ausmus, who caught more games than any other player in team history, and Castro sped through the Minor Leagues as the team's backstop of the future. That future was slowed by a devastating knee injury that cost him the entire 2011 season and a subsequent broken foot that slowed his progress.

Castro's lack of a mentor and lost time because of injury means he's at camp trying to establish himself as a Major League starting catcher. And he's not doing it alone.

Houston general manager Jeff Luhnow added former Cardinals bullpen coach Jeff Murphy to the staff this year, hoping he can held mold Castro into a top-notch catcher the same way he did with Gold Glove winners Mike Matheny and Yadier Molina in St. Louis.

"One of my priorities this year was to make sure Castro had someone nearby that had the type of experience to give him the type of coaching he needs," Luhnow said. "He's got everything he needs to be a premier defensive catcher -– he's athletic, he's strong, he's smart. The missing element may just be having that mentor alongside him that can give him some tips."

The difference between a good catcher and a great catcher is subtle, and the Astros are hoping Murphy can bring out the best in Castro. After missing all of 2011 following surgery to repair a torn ACL in his right knee, Castro hit .257 with six homers and 29 RBIs in 87 games last year, hitting four homers in the final six games of the season.

The Astros are confident Castro's offense will continue to progress, and this spring will concentrate on tightening up his defense. He had trouble blocking balls in the dirt last year and wound up with eight passed balls in about a half season of work behind the dish.

"I know that I didn't play the way I wanted to definitely," Castro said. "I learned a lot and saw some progression as the year went on, and I thought I tried to make some adjustments where I could. Having Murph in camp here has been fantastic. We went to work Day One, and I can tell I'll definitely be ready and healthy and prepared as I've ever been to the start the season."

Murphy, 42, is a wealth of catching knowledge. A former catcher in the Cardinals system, he learned the craft of catching from longtime Cardinals bullpen coach Dave Ricketts.

"He was the guru, the father of all of us catchers coming out of the Cardinals organization," Murphy said. "He simplified it as best you could. The thing I learned from him is everybody is different and you learn to build off that."

Murphy worked with Molina from the day he was drafted in 2000 through the '11 season, which was his final campaign in St. Louis. Molina enters this year having won five consecutive Gold Gloves. Murphy had Molina working early on defense in the batting cage each day during the spring, and he's doing the same with Houston's catchers, including Castro.

"Mr. Ricketts always had us in the cages first thing in the morning, and that's where I feel like you get your best work done, you get to iron out the little things that might be going on during the day and the young guys can listen to the older guys," Murphy said. "You work on the simple stuff that kind of gets overlooked when it comes to receiving."

Castro, 25, is soaking it all up.

"He's shared a lot of good ideas to stay fresh throughout a long season," he said. "Just those kinds of things that I think more than anything will help me stay on top of my game all year long and not have any lulls."

Murphy has no doubt in Castro's skills and desire to succeed, and he chalks up his defensive struggles in 2012 to health more than anything else.

"A lot of things suffer when it comes to health," Murphy said. "That wasn't the Jason Castro I saw in 2010 when we played the Astros. So I'm not worried about Jason Castro. I'm not worried about his work ethic, and I'm not worried about his ability behind the plate. If he's healthy, he's going to be able to lead the team and do the job he needs to do to catch, block and throw."

Blocking balls, Murphy said, is a mindset. A catcher has to want to get down and stop the ball, and he has to be able to anticipate a ball in the dirt. He has to have confidence.

"If you're confident and you have the attitude, you can tell your pitchers, 'Don't worry about. I don't care if that guy's on third. You throw it in the dirt and I'll block it,'" Murphy said. "What it does is instill confidence in your pitcher to make that good pitch instead of worry about it."

This will be a big year for Castro, who had a full offseason to get prepared for the grind of the season. Astros manager Bo Porter expects him to be able to catch about 125 games, which would be a huge jump in workload over last year.

"It's time for him to establish himself a No. 1 catcher and as a guy that can help you both ways," Luhnow said. "He showed us last year he could help us with the bat, and I want him to show us this year he's the guy all the pitchers want to throw to."