Brad Mills, right, manages his first exhibition game Thursday for Houston - a 15-5 win over Washington. "He's pretty intense," the Astros' Michael Bourn says. Rob Carr

KISSIMMEE, Fla. - Rookie manager Brad Mills bounces around the practice fields at the Houston Astros' spring training complex, always in the middle of the action.

The former University of Arizona star, 53, smacks grounders to his infielders on one field, throws batting practice on another, offers advice to pitchers fielding bunts on another.

Even when he's not working with his players, Mills often takes practice swings at the air with a black fungo bat, like he's ready to step into the batter's box again himself.

"Here we go, guys, let's go!" Mills barked from the infield grass as his players started running bases during a recent workout.

Mills, Boston's bench coach over the previous six seasons, succeeded Cecil Cooper as Houston's manager last October. The Astros offered the job to Manny Acta, but he decided to become Cleveland's manager.

Mills won over the Astros' brass with his energy and enthusiasm, traits the team seemed to lose in the last months of Cooper's two-plus seasons. Cooper was fired with 13 games to go in 2009, and Houston limped to a 74-88 record.

A week into spring training, Mills already has transformed the mood in the clubhouse.

"You have be an idiot not to recognize the fact that guys are a little more upbeat," infielder Geoff Blum said. "As far as personality of the leadership, it's definitely changed. Things were a little more somber last year, and then you have Brad Mills come in, who's energetic, intense and well-organized."

Mills has dedicated his life to baseball, though he played only four seasons in the majors (1980-83) before a right knee injury ended his playing career. He hit .256 with one home run and 12 RBIs in 106 games with Montreal.

His biggest claim to fame as a player may be that he was Nolan Ryan's 3,509th strikeout victim, the one that made Ryan baseball's all-time leader ahead of Walter Johnson.

Mills managed 10 seasons in the minor leagues before becoming Terry Francona's first base coach in Philadelphia in 1997.

The two played together at Arizona in the late 1970s, and again with the Expos. Mills, a third baseman, earned second-team All-America honors in 1978.

Current Astros' general manager Ed Wade became the Phillies' GM when Francona and Mills were there, and he fired Francona in 2000. The Red Sox hired Francona as their manager in 2004 and Mills joined the staff as the bench coach.

Boston won the World Series in 2004 and '07, with Mills gladly doing much of the behind-the-scenes work in support of his manager.

"Millsie will communicate with those young guys," Francona said. "He'll treat the veterans with respect. He got an opportunity probably way too late, for whatever reasons. But, he'll do a great job."

Mills called every player on the roster in the offseason to introduce himself and to explain his open-door policy of communication.

"Hopefully, they feel a freedom to become the player they're capable of (becoming)," Mills said.

Mills gave a rousing speech before the team's first full-squad workout - the best owner Drayton McLane said he has heard by an Astros manager in 18 years.

"He's pretty intense," Houston center fielder Michael Bourn said. "You need somebody like that sometimes to get you going."