The Seattle Mariners placed starting pitcher Taijuan Walker on the 15-day disabled list on Wednesday with right foot tendinitis.

The move comes a day after Walker left a start early for the third time this season because of a foot problem.

Walker (4-7, 3.66 ERA) yielded five hits and five runs to the Houston Astros before leaving after four innings with discomfort in his right foot. He also left early because of his foot on June 14 and June 19.

Taijuan Walker is headed to the disabled list after being diagnosed with having right foot tendinitis. Troy Taormina/USA TODAY Sports

"What we're seeing is not good and is probably not in his or our best interest to kind of just keep running him out there," manager Scott Servais said Wednesday.

Servais added that Walker will see a specialist soon.

Walker said he is frustrated that this issue has lingered for so long.

"I feel like I just haven't had my best stuff," he said after Tuesday's shortened start. "My [velocity is] down. My changeup isn't as sharp. Nothing is really as sharp, just because I can't get into my legs and get after it. It's probably not best for me to go out there and pitch, because I can't give it 100 percent."

The Mariners lost to the Astros 5-2 on Tuesday.

"First two innings was good. I was able to drive," Walker said. "After the second inning, I had no legs. Everything was up. Everything was running back to the plate. I just couldn't drive it in there."

The news Wednesday wasn't all bad for the Mariners. Ace pitcher Felix Hernandez will be ready for a rehab assignment after pitching a simulated game.

Hernandez has been on the DL since June 1 with a strained right calf. If all goes well with his rehab appearances, the Mariners are eyeing a July 20 return for Hernandez.

"I feel strong. I feel really good. I think it's fresh right now," Hernandez said of his arm. "I can't wait to be out there again."

Information from The Associated Press was used in this report.