During that stretch, the rotation has allowed 64 hits -- including 14 home runs -- in 41 1/3 innings as a team that led the American League in ERA for most of the early going suddenly has looked vulnerable.
"It has been a rough stretch, no doubt," Mariners manager Scott Servais said. "We're well aware of it, knowing that the reason we're in the position we are record-wise is because of our starting pitching. But it's been a struggle for the last six or seven days getting deeper in games, something we've got to get corrected."
Walker lacked his normal command and velocity for much of Friday's five-inning outing, though his biggest problem turned out simply to be Adrian Beltre. The Rangers third baseman went 2-for-2 with a walk and five RBIs against Walker, accounting for much of the damage on a line that finished with nine hits, six runs, four walks and two strikeouts.
Beltre is now batting .538 (7-for-13) with three doubles, one homer and eight RBIs against Walker.
Walker opened the season by going 2-0 with a 1.44 ERA in four April starts, but since then is 0-6 with a 5.77 ERA in seven outings.
"He's in developmental mode right now and that's hard to do at the big league level," Servais said. "He's just having a hard time finding a secondary pitch that's going to work. Tonight he got hurt on a couple again, a slider, a changeup, and it just continues to happen over and over. We need to continue to work. He's a very talented guy and certainly we think he has a very high ceiling, but right now he's in a bit of a rut and we've got to find a way out of it."
Walker attributed his tough start to not coming out aggressively enough. His fastball was in the 90-92 mph range in the first few innings and it wasn't his final two batters in the fifth -- with the bases loaded -- that he reached back and hit 94-95 mph on the gun in striking out Mitch Moreland and Elvis Andrus to end his 107-pitch outing.
"My first couple innings there just wasn't any intensity," Walker said. "I was kind of feeling my way through, I guess, not pumping it in there like my last inning. I have to figure it out. It's just being intense and really going out there and going right after them with conviction. I have to get after it from pitch one."
Servais definitely noticed the increased velocity at the end of Walker's outing.
"His back was against the wall, he wasn't coming out and the bases were loaded," Servais said. "It's in there. He's a talented guy and we certainly need him. And he'll get it back on track. But we have to continue to work and find something that is going to be consistent for him."
Robinson Cano said Walker just needs time to grow.
"He's young. We all go through that," said Cano. "When I came up, I used to swing at everything. You've got to let him mature. He'll be one of the best in this game. He's got the stuff, he's just got to learn how to use it."