BALTIMORE -- Given how well former Mariners prospect Chris Tillman has thrown this season for the Orioles, and given his history against Seattle -- 6-0 in eight career starts entering Wednesday -- Mariners manager Scott Servais knew he needed his own starting pitcher to be at his best.
Ultimately, Taijuan Walker conceded after the Mariners fell to the Orioles, 5-2, on Wednesday, he was not.
"I didn't have it today," Walker said after allowing four runs (three earned) on five hits and two walks in five innings. "The slider felt good, but I was really throwing too much offspeed, not going to my strength -- my fastball -- and not really trusting it."
Walker is now 0-3 with a 5.23 ERA in four starts in May after going 2-0 with a 1.44 ERA in four starts in April.
After allowing just one home run in his first five starts this season, the right-hander has now been victimized by the long ball five times in his last three outings, including twice against Baltimore on Wednesday.

Walker allowed back-to-back homers to Mark Trumbo and Matt Wieters in the second, as the Mariners fell behind early, 2-0.
"I threw a hanging curveball and Trumbo is a power hitter," Walker said. "He doesn't miss mistakes, and that's what it was -- a mistake."
"The curveball wasn't there at all," Servais said.
Walker settled down after the back-to-back home runs, retiring seven straight, before Trumbo and Wieters again combined to put the Orioles on the board. A one-out single from Trumbo in the fourth was followed by a Wieters RBI double to give Baltimore a 3-2 lead.
Things unraveled in the fifth, which began with Walker issuing a leadoff walk to Hyun Soo Kim. One batter later, Walker was charged with an error when he overthrew shortstop Ketel Marte covering second base on a Joey Rickard bunt. Instead of potentially turning a double play, Walker was in a jam with two on and none out.
"I didn't realize I had that much time, and I tried to be too quick with it and just threw it away," Walker said of the error.
A walk to Chris Davis two batters later loaded the bases for Trumbo with two out, when Walker threw a wild pitch that allowed Kim to score from third.
"Bases loaded, I didn't want to make a mistake and try to do too much and I just left it up," he said of the pitch that sailed beyond the reach of catcher Chris Iannetta.
Trumbo eventually grounded out to short on what proved to be Walker's final pitch of the night. The 26-year-old threw 91 pitches, 53 for strikes, in his shortest outing of the season, excluding his May 6 start in Houston in which he left after two innings due to neck spasms.
Since beginning the season with four straight quality starts, Walker hasn't completed six innings in any of his last four outings.
"There wasn't quite the same crispiness to his stuff that we saw last time out," Servais said, referring to the five scoreless frames Walker threw May 11 against the Rays, before he surrendered a grand slam in the sixth.
"Obviously the error -- the comebacker error -- a couple of home runs he gave up, he just wasn't on top of his game tonight. He battled, he kept us there, but we've certainly seen better stuff from him."
"Rhythm was a little off," said Walker, who is now 2-3 on the year with a 2.95 ERA. "I didn't throw my best, I didn't really locate too well, I kind of got behind. ... I was throwing a lot of offspeed pitches early and not really establishing my fastball, so I wasn't able to throw that for strikes."