Izturis was the Opening Day shortstop, but he moved to second base when Howard Kendrick strained his left hamstring on April 13 in Seattle. With Chone Figgins (strained right hamstring) joining Kendrick and Izturis on the DL, rookie Sean Rodriguez has filled the void at second with capable defense and timely hitting.
"I'm ready to play," Izturis said before taking batting practice. "My back feels good."
Izturis -- who will support Aybar at short and is another option at third until Figgins returns -- has made 15 starts at second base, six at shortstop.
Izturis experienced back spasms on April 26 in Detroit while playing second base. He'd hit safely in seven of eight games (.360) to lift his average to .206 from a low of .109.
One of the team's best clutch hitters in 2007 while moving back and forth from third to second, Izturis hit .406 with runners in scoring position and finished the season with 51 RBIs in 336 at-bats.
O'Day, 25, was one of the pleasant surprises of the season, earning a spot on the 25-man roster after a brilliant Cactus League performance as a non-roster invitee.
A side-armer from the University of Florida, O'Day fashioned a 3.43 ERA in 16 appearances, losing his only decision. He had 13 strikeouts while issuing 11 walks (six intentional) in 21 innings.
"It's a tough decision [to replace O'Day with Arredondo]," manager Mike Scioscia said. "Darren was throwing the ball well for us.
"Right now, we need guys with a little length. Arredondo is a power arm, somebody we want to look at.
"Darren's not a finished product. We want him to go down and work on some things in Salt Lake. He'll come back a better pitcher. He's shown he can compete in the Major Leagues. He's not the first guy to go back and brush up on a couple things to reach his potential."
Arredondo, 24, hails from San Pedro de Macoris, known as the cradle of Dominican Republic shortstops. Arredondo made the conversion from shortstop to pitcher in 2004, his second professional season, after signing as an 18-year-old free-agent infielder in 2002.
In 15 appearances at Salt Lake, Arredondo is 1-1 with a 2.12 ERA. He has 15 strikeouts against four walks in 17 innings, allowing 12 hits and hitting one batter.