"Trembley managed before, and I think it's a good opportunity for him to do whatever he can to assist Bo on the bench, and it gives Eduardo a different experience in a different role," Astros general manager Jeff Luhnow said. "They were both very valuable to us last year, and we really felt like the managerial experience Trembley has could be more useful on the bench standing right next to Bo than standing at third base."
Dan Radison, who was assistant hitting coach last year, has been named a special assignment coach and will split time between the Astros and their Minor League affiliates.
"Radison, Mallee and Ralph are all very well-aligned in terms of hitting philosophies," Luhnow said. "We feel good about the contributions all three of those guys had last year. Ralph and John worked together in the past, and we wanted to give Ralph the opportunity to spend more time with big league players, so Radison will get a chance to spend half the year with the big league club and half the year roving around the Minor Leagues, which he had done the year before."
Luhnow said the Astros are talking with Jeff Murphy about a role teaching prospects in the Minor Leagues. He spent last season as the club's Major League bullpen catcher and catching instructor.
"He did a terrific job teaching the Major League catchers very specific things, and we saw the results of [Jason] Castro's improved blocking and throwing," Luhnow said.
Listach, 46, joins the Astros from the Dodgers, where he served as the organization's Minor League infield coordinator in 2013. Prior to last season, Listach coached on the Major League staffs for the Cubs (2011-12) and Nationals (2009-10). He also has nine years of Minor League coaching experience in the Cubs' system from 2000-08. Listach played in six Major League seasons, which included time with the Brewers (1992-96) and the Astros (1997), and he won the 1992 American League Rookie of the Year Award. He is a resident of the Houston area.
Luhnow said Listach fills the team's need for an infield instructor on the staff to help shortstop Jonathan Villar and second baseman Jose Altuve continue to develop.
"He's got a lot of experience, not only as a player playing the infield, but also as a coach," Luhnow said. "I think we have two very important assets in the middle infield, and with more coming, we really feel that was one area of instruction that we didn't have consistently at the big league level last year. Pat's got experience and a great resume."
Bjornson, 44, returns as the club's bullpen coach, the same position he held for the Astros in 2012. He spent last season working as the organization's roving pitching instructor. Bjornson has 15 years of coaching experience in professional baseball, mostly spent as a pitching coach. He also played three seasons of Minor League Baseball (1991-93) in the Astros' system.
Dickenson, 65, will take over as the assistant hitting coach after spending the 2013 season as the club's Minor League hitting coordinator. He has been a Minor League hitting coordinator for 20 seasons (1990-92, 1995-2009, 2013) for seven different organizations. The 2014 season will be his 36th season as an instructor at the professional or collegiate level and his first on a Major League staff.
Next year will mark Trembley's 30th season in professional baseball and his second consecutive season with the Astros. He was the manager of the Orioles for parts of four seasons (2007-2010) and also spent 20 seasons as a Minor League skipper, which included managing Porter at three different levels while with the Cubs organization (1995-98).
Perez, 44, joined the Astros last year after serving as the Marlins' hitting coach for nearly two seasons (2011-12). He has also worked as a special assistant to the baseball operations department for the Indians, a role which included considerable time in uniform providing instruction at the Major League and Minor League levels. Perez played parts of 13 seasons (1993-2006) in the Major Leagues with the Angels, Reds, Cardinals, Rays, Indians and Mariners. Following his playing career, he spent several seasons as a baseball analyst for ESPN, working the postseason and for Baseball Tonight.
Strom, 64, spent the last six seasons (2008-13) with the Cardinals organization, serving as the Cardinals' Minor League pitching coordinator (2012-13) and Minor League pitching instructor (2008-11). This will be Strom's third stint as a Major League pitching coach and his second with Houston, having been in the same position for the Astros in 1996 and the Royals in 2000-01.