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"All Mike's been doing since we started these playoffs is DH," manager Ron Washington said of Young. "I needed to get him engaged. It might jumpstart his bat a little more instead of always thinking about hitting. It gets him a little more involved."
Mitch Moreland, who has started at first base in all but Game 1 of the AL Division Series, will be off the bench. He is 2-for-17 in the playoffs and 1-for-7 with three strikeouts in the ALCS.
The change also allows Napoli to get a break from catching and avoids having him behind the plate for four consecutive days, something he didn't do in the regular season. It gives Torrealba his first action of these playoffs as well. He batted .273 in 113 games this season (396 at-bats) with seven homers and 37 RBIs. His playing time decreased some in the final weeks as Napoli's bat started heating up and Nelson Cruz returned from the disabled list.
Chavez, a left-handed hitter, gives the club some speed in a big outfield.
"My gut tells me I need to play Endy tonight," Washington said.
Chavez hasn't played at all so far this postseason. He filled in nicely during various outfield injuries in 2011 and hit .301 with five homers and 27 RBIs in 256 at-bats. He also stole 10 bases.
Young started 36 games at first base for Texas in 2011 and had three errors and a .989 fielding percentage.
Meanwhile, for the Tigers, manager Jim Leyland announced that Delmon Young was scratched from Tuesday's lineup, replaced by Andy Dirks.
Leyland said he does not know what Young's availability will be for the rest of the AL Championship Series.
Richard Durrett covers the Rangers for ESPNDallas.com. ESPN.com's Buster Olney contributed to this report.