Saunders faced 15 batters, and 11 reached base on eight hits, two walks and a costly error by second baseman Adam Rosales that led to five unearned runs in the first. Saunders threw 53 pitches.
"Just a little case of normal Spring Training dead arm," Saunders said. "Warming up, my arm felt great, but nothing was coming out. ... No crispness, everything seemed to flutter up there, no snap on it. Everybody goes through a dead arm period. I just need to relax a little bit, and it should be fine for my next start."
Saunders, who signed two weeks into camp and has made four starts, is competing for one of two remaining spots in the Rangers' rotation along with Colby Lewis, Robbie Ross and Tommy Hanson.
"They know what I'm capable of," Saunders said. "I've shown in previous starts that the stuff is there. It's just a little case of dead arm."
Padres starter Matt Wisler, who was filling in for an injured Josh Johnson and has an outside chance of making the Padres' rotation, allowed five runs in 2 2/3 innings.
"Wis came out with a good first inning, but his fastball command got a little erratic on him," Padres manager Bud Black said. "But overall, his stuff was good. He just couldn't hone in on throwing consistent strikes."
Leonys Martin had four hits and two RBIs, while Michael Choice had three hits and three RBIs for the Rangers. Choice doubled off Friars reliever Alex Torres in the third inning, with Prince Fielder scoring and Martin called out at the plate. But after a challenge by manager Ron Washington, the play was overturned and Martin was awarded the run.
Rangers reliever Michael Kirkman pitched three scoreless innings.
Up next: The Padres travel to Cubs Park in Mesa, Ariz., for a 7:05 p.m. PT game on Monday. Eric Stults, who now likely becomes the No. 4 starter in the rotation after Johnson suffered a forearm injury, gets the start for the Padres. He's got a 7.15 ERA in four starts this spring, and has allowed 14 hits in 11 1/3 innings. He's been sharper as of late. Last season, Stults led the Padres in victories (11) and innings (203 2/3).