"He did a tremendous job for us," McClendon said. "He knew going in he'd be stretched tonight if he came in. He was up for the challenge."
Leone had been sent down to Tacoma just prior to Opening Day after a poor spring, but said he felt good about his 36-pitch performance.
"I thought tonight was a huge step for me getting back to where I was last year and years past," said the 23-year-old. "I felt really good out there. I was throwing strikes and keeping the ball down. I'm taking a positive out of tonight despite the loss."
Wilhelmsen hurt his elbow in what McClendon called "a freak accident," as the 6-foot-6 right-hander was loosening up in the bullpen in Oakland on Saturday when teammate Danny Farquhar collided with his right arm.
"I just got up to stretch a little and was doing some tree trunks [twisting exercises] and -- just bad timing -- Danny ran by me and I hyperextended my arm a little bit," Wilhelmsen said. "It felt tender when it happened, but not excruciating.
"I'm expecting to throw sometime later in the week, so it's pretty minor," he said. "But we need some help, so it's the right move."
Wilhelmsen, 31, has appeared in two games this season and given up five hits and two runs in 2 2/3 innings. His DL move is retroactive to Saturday, the day after his last appearance, in Oakland, so he'll be eligible to return on April 26.
Wilhelmsen played a critical role in the Mariners' bullpen last season, when he went 3-2 with one save and a 2.27 ERA in 57 appearances, including two starts. He held opposing batters to .171 batting average in 79 1/3 innings.
Wilhelmsen expects to begin throwing again soon. When he does, he'll keep an eye out for his teammate Farquhar.
"I knew he was a fast runner when he went in to pinch-run last year," Wilhelmsen said with a smile, "but now I've seen firsthand that he is a lot faster than I thought."