The 25-year-old switch-hitter had three hits, drove in two runs and made a highlight-worthy play behind second base in Pittsburgh's 4-3 victory over the Cardinals in the series opener at Busch Stadium.
"He's a ballplayer," Pirates manager Clint Hurdle said before Tuesday's game. "I do hear comments from time to time that he can't do this and he can't do that. We live in a society that we're so quick to try and point out how smart we are and something that somebody can't do."
"You let the kid play and you watch him play. He comes to play. He comes to win. He's going to do whatever it takes on the offensive and defensive side of the ball to win a ballgame. He'll lay out. Does he have work to do? Can he improve? All of us can. I like the way he embraces the game and he has embraced this opportunity."
Walker took a hit away from Cardinals third baseman David Freese and may have thwarted a St. Louis rally in the fourth inning on Monday when he made a sliding stop to his right behind second base and threw Freese out at first for the second out of the inning.
It was an impressive play for a guy who had played all over the field before finding a home at second base for the Pirates last season as a rookie.
Walker's bat hasn't been a question so far this season and has played a big part in Pittsburgh's 3-1 start. He entered Tuesday night's game hitting .412 (7-for-17) with three doubles, one home run, seven RBIs, four runs scored and a .444 on-base percentage.
His seven RBIs lead the National League.
The 11th overall pick in the 2004 Draft, Walker finished tied for fifth in the NL Rookie of the Year Award voting last season after hitting .296 with 29 doubles, three triples, 12 home runs, 66 RBIs, 57 runs scored and a .349 OBP in 110 games.