Walker, the son of former major league pitcher Tom Walker, celebrated his promotion to everyday player by getting two hits as the Pirates beat the Cubs 2-1 on Monday. Walker is hitting .321 in seven games with the Pirates, the identical average he had in 43 games with Triple-A Indianapolis.
Walker is the first of a number of Pirates prospects who are expected to reach the majors this season, including third baseman Pedro Alvarez, outfielder Jose Tabata and right-hander Brad Lincoln.
"That vote of confidence helped a lot, and not just today," Walker said. "Mentally, it helps."
Iwamura, acquired from Tampa Bay for reliever Jesse Chavez during the offseason, didn't take the demotion well despite his .172 batting average -- the third lowest in the majors for any batter averaging at least 3.1 plate appearances per game.
Manager John Russell said he was "upset," and Iwamura didn't speak to reporters.
"Hopefully, he'll take it the right way and works hard," Russell said.
The Pirates gambled by picking up Iwamura's $4.85 million contract even though he missed most of last season following left knee surgery. Iwamura is wearing a brace on his left leg, which is iced from hip to ankle after every game, and his right knee also is iced following games.
Partly because of his knee problem, Iwamura has shown little range in the field, often giving up on routine groundballs hit either a few feet to his left or right.
Pirates fans have begun booing Iwamura whenever he steps to the plate, as they did when he grounded out weakly as a pinch-hitter Monday in the seventh inning.
Walker was the Pirates' top pick as a catcher in 2004, moved to third base in 2007 but didn't start playing second base until spring training. He has made four starts at third and three at second with Pittsburgh.
Walker had several promising minor league seasons before breaking out this season with six home runs, 18 doubles and 26 RBIs at Indianapolis.
"That's been the biggest key to my success, my belief in myself, and not just against Triple-A competition," Walker said. "I've always believed I was a major league player. But there's a certain confidence that comes with it, too, when you step into the box and when you step onto the field. I didn't have that until this year, but I feel that now."
Walker has four multiple-hit games in his last six starts.
"I'm happy to be here but, at the same time I'm not satisfied. I want to help this team immediately and be a go-to type player," Walker said. "That's not my role right now, my role is to play my part and continue to do the right things and move forward."
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