The message the Mariners chose to send earlier this week to an inconsistent Taijuan Walker by demoting him to the minors forced a scramble Friday to determine a starting pitcher for the series opener against Oakland.
The Mariners settled on a promotion for veteran right-hander Joe Wieland, a nine-year professional with limited big-league time who is 11-5 with a 5.38 ERA this season at Triple-A Tacoma.
Wieland, 26, started Friday when the Mariners carried a six-game winning streak into their weekend series at the Oakland Coliseum. Walker will start Saturday for Tacoma at Memphis (Cardinals).
While Wieland’s overall numbers aren’t imposing, he won his last five starts at Tacoma while compiling a 2.37 ERA over 30 1/3 innings.
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"Joe has been throwing the ball very well in Triple-A," manager Scott Servais said. "His last five have been outstanding."
The Mariners cleared space Thursday for Wieland on their 25-man roster by optioning right-hander Jarrett Grube to Triple-A Tacoma. Grube started Friday for the Rainiers at Memphis.
Since Wieland was not on their 40-man roster, the Mariners required another space-clearing move; they designated Tacoma outfielder Daniel Robertson for assignment.
Walker has long been viewed as the heir apparent to Felix Hernandez atop the Mariners’ rotation, but he was 4-7 with a 4.10 ERA in 17 starts when optioned Monday to Tacoma.
The move came two days after he lasted just four innings against the Los Angeles Angeles in his first start after spending a month on the disabled list because of tendinitis in his right foot.
At the time, Servais left little doubt the decision was performance-based. Walker was 2-7 with a 5.12 ERA over his last 13 starts.
"When you’re one of five starting pitchers," Servais said, "there’s a certain level of expectation. You’ve got to go deeper in games. You’ve got to be competitive.
"He’s had a few nagging injuries, but where we’re at as a club dictated (the decision) as much as anything."
The Mariners acquired him in a Jan. 12 trade from the Los Angeles Dodgers for infielder Erick Mejia. Wieland is 1-5 with a 5.85 ERA in 11 big-league games, including nine starts, over parts of three seasons with San Diego and the Dodgers.
By promoting Wieland, the Mariners opted to keep rookie lefty Ariel Miranda in the bullpen.
Miranda pitched six innings Aug. 4 against Boston in his first big-league start. He was scheduled to start Friday, in Walker’s place, before pitching one inning Tuesday as a reliever in a 15-inning victory over Detroit.
Grube, 34, spent just one day in the big leagues after his contract was selected Wednesday from the Rainiers. The Mariners required a fresh arm after using their entire bullpen Tuesday in a 15-inning victory over Detroit.
Robertson, 30, was 5-for-19 in nine games for the Mariners over a two-week span in July. He spent most of the season at Tacoma, where he batted .281 with six homers and 40 RBIs in 95 games.
Servais pointed to the emergence of outfielder Guillermo Heredia, who recently returned to Tacoma, as a factor in the decisions to designate Robertson.
"I hope we don’t lose Danny Robertson," Servais said. "I hope we continue to keep him in the organization."
The Mariners now have 10 days to trade, release or (if he clears waivers) send Robertson to the minors on an outright assignment.
UPDATES ON PAXTON, CISHEK
Left-hander James Paxton will test his sore elbow Saturday by throwing a bullpen workout and remains a tentative choice to return to the rotation early next week against the Angels in Anaheim.
Former closer Steve Cishek, meanwhile, could be ready to begin a rehab assignment by the end of the weekend in his recovery from a torn labrum in his left hip.
Paxton was hit by a line drive in the ninth inning of an Aug. 7 victory over the Angels at Safeco Field. He reported lingering tightness early in the day but said he felt better after playing catch on flat ground.
By throwing a bullpen workout Saturday, Paxton would be positioned, barring any setbacks, to start Tuesday or Wednesday in Anaheim.
Cishek received a cortisone shot after being diagnosed earlier this month with a torn hip labrum. He has already progressed to being able to throw from the mound in a bullpen workout.
"By the time we get off this road trip," Servais said, "he should be available for us."
A ZYCH SIGHTING
Plans called for right-handed reliever Tony Zych to begin a rehab assignment Friday at Peoria in the Arizona Rookie League. He hasn’t pitched since May 1 because of tendinitis in his rotator cuff.
Zych, 26, was 1-0 with a 3.00 ERA (four earned runs in 12 innings) and 19 strikeouts over 10 appearances prior to suffering the injury.
***Right-hander Evan Scribner, 31, has made two rehab appearances in his recovery from a torn back muscle (right latissimus dorsi muscle) that surfaced in spring training.
The Mariners entered the weekend at 8-2 in August, and one big reason was a pitching staff that compiled an American League-best 2.39 ERA in that span.
The bullpen has been even better: its 1.44 ERA in August (five earned runs in 31 1/3 Innings) was the best in either league while limiting opponents to a .178 average (19-for-107).
The rotation had seven quality starts in 10 games while compiling a 2.84 ERA.
Double-A Jackson outfielder Tyler O’Neill is mounting a triple-crown threat in the Southern League. He entered the weekend leading the league with 86 RBIs and a .306 average and ranked second with 20 homers.
O’Neill, 21, was only one homer behind the league leader, Chattanooga (Twins) outfielder Daniel Palka, who has been promoted to Triple-A Rochester. O’Neill held a six-point lead in the batting race and had a 10-RBI lead.
The Southern League season runs through Sept. 5. The league’s last triple-crown winner was outfielder Mike Reinbach of the Asheville Orioles in 1972.
It was 20 years ago Saturday — Aug. 13, 1996 — that Randy Johnson returned from a back injury and pitched four shutout innings in relief as the Mariners ended a seven-game skid with a 9-5 victory over Kansas City at the Kingdome.
It was the second and final save of Johnson’s 22-year career, which culminated in his 2015 induction into the Hall of Fame. His other save occurred in 1993 against Baltimore at the Kingdome.
Joe Wieland is the 29th pitcher used this season by the Mariners, which is a franchise record. He also was the 12th different pitcher to start a game…the Mariners entered the weekend with 80 games with two or more home runs. No other club had more than 68…the Mariners carried a seven-game winning streak at the Oakland Coliseum into the weekend series. Even so, they are 118-180 in their history at the Coliseum.
The Mariners and Athletics continue their three-game series at 6:05 p.m. Saturday at the Oakland Coliseum.
Right-hander Hisashi Iwakuma (13-7 with a 3.79 ERA) will face Oakland right-hander Kendall Graveman (8-7, 4.29). The game can be seen on Root Sports Northwest and heard on 770 KTTH.
Bob Dutton: @TNT_Mariners