ARLINGTON, Texas -- Struggling prospects Mike Olt and Cody Buckel began their search Tuesday for what's behind their shockingly poor starts to the season.

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Olt, the Rangers' second-highest ranked prospect behind shortstop Jurickson Profar, saw team doctors Tuesday after informing club officials he was having issues with his vision. It could be as simple as the Triple-A Round Rock infielder needing contacts or glasses, general manager Jon Daniels said, or it could be something more. Daniels didn't have a diagnosis for Olt before the Rangers' game Tuesday against the Chicago White Sox.

Buckel, a right-handed pitcher who has been having issues with his control at Double-A Frisco, was moved from the starting rotation to the bullpen Tuesday. Buckel, the club's eighth-best prospect, has 25 walks in 18 innings. He had three walks and didn't record an out in his most recent start, against Corpus Christi on Saturday.

Olt's vision problems might help explain why he's off to a dismal start. Olt, a career .282 hitter in the minors entering the season, entered Tuesday batting .139 in 72-bats and has one home run after tying for the Texas League lead with 28 home runs last year.

"It would make sense if that's what has developed," Daniels said Tuesday.

Buckel heads to the bullpen after not pitching more than three innings in his five starts this season. He had a season-high six walks in three innings at San Antonio on April 22 and has walked at least five in three other starts.

Buckel will take up some innings in what has been a dominant bullpen in Frisco. But Daniels said the club thought it was better that Buckel sort things out in Double-A rather than at extended spring training.

"It's nothing physical with Cody," Daniels said. "He's been scuffling all season."

Both Olt's and Buckel's names came up in trade talks during the offseason.

Other Rangers notes:

Baker in, Murphy out: Jeff Baker got the start in left field against White Sox left-hander Jose Quintana, giving struggling starter David Murphy an extra day off. Murphy, batting .176 with two home runs, has a track record that says he will get his bat going.

"He's missing pitches that he usually gets," manager Ron Washington said.

Murphy and third baseman Adrian Beltre both have started slow. Beltre is batting .221 with four home runs and only nine RBIs.

"You know their track record is there," Washington said. "You just have to be patient."

More on Beltre: Beltre said Tuesday that he's not concerned with his slow start, noting he always has been a warm-weather player. Beltre is batting .107 with runners in scoring position.

"I know I'm going to be OK," Beltre said. "I would say I've been average. There hasn't been a time when I've felt great and there's not a period where I've felt terrible."

Randy Wells retires: Veteran pitcher Randy Wells, who has been at Triple-A Round Rock, has retired, Daniels said Tuesday. Daniels said the 30-year-old Wells told club officials that he didn't have the same level of desire for the game.

It's Joseph Ortiz: The Rangers said Tuesday that reliever Joe Ortiz has been asked to be called Joseph Ortiz from this point forward. Ortiz has allowed runs in his past three appearances, but the Rangers didn't provide that as the reason he is going with Joseph.