BOSTON — Mariners lefty Wade Miley started with a joke Friday when asked to explain why he was heading to the 15-day disabled list because of a sore shoulder — specifically termed an impingement.
"They wanted to save my ERA," he said. "They didn’t want it to get any worse."
The actual cause, Miley acknowledged, was a lingering tightness following his June 12 start against Texas at Safeco Field.
"It’s been nagging me for a little while," Miley said. "A couple of weeks. A couple of starts. It just never bounced back after the last start. I wanted to pitch but, at the same time, I wanted to be smart.
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"Instead of trying to limp through a bunch of starts and try to get to the All-Star break, I’m going to take a couple of days off and try to get it right and go from there."
The Mariners also moved to bolster their weary bullpen by recalling two relievers, Jonathan Aro and David Rollins, from Triple-A Tacoma prior Friday’s start to a three-game weekend series against Boston at Fenway Park.
Summoning two relievers required another corresponding move. In addition to putting Miley on the disabled list, the Mariners designated reliever Steve Johnson for assignment.
"Our bullpen is just beat up right now," manager Scott Servais said, "and we thought getting a couple of fresh arms in here would help."
The relief corps chewed through 15 innings over the three previous days at Tampa Bay but, tellingly, Johnson was relatively fresh. He hasn’t pitched since Tuesday, when he worked one inning.
But designating Johnson for assignment clears a space on the 40-man roster, which the Mariners are expected to use Saturday by promoting right-hander Adrian Sampson from Tacoma to fill Miley’s spot in the rotation.
Johnson was 1-0 with a 4.32 ERA in 16 appearances but had allowed seven runs in his last 5 1/3 innings over six outings. If he clears waivers, he is likely to be assigned to Tacoma.
The Mariners backdated Miley’s time on the disabled list to June 13, which means he is eligible to return on June 28. Miley said he "absolutely" expects to be ready to start that night against Pittsburgh.
Servais, while more cautious, didn’t disagree.
"We thought it was best to shut (Miley) down and give him a chance to regroup," Servais said. "He’ll only miss, if everything goes well, a couple of starts. And we’re optimistic that it is only going to be a couple of starts."
The Mariners are now down two starters in their rotation.
Right-hander Felix Hernandez hasn’t pitched since May 27 because of a strained right calf muscle. His latest exam on Wednesday produced positive results, and he has progressed to throwing from a standing position.
Even so, Hernandez isn’t expected to return before the All-Star break.
There is positive news:
Right-hander Taijuan Walker remains on track to start Sunday’s series finale against the Red Sox after leaving his last start because of inflammation in the tendon that attaches the calf muscle to the bones on the inside of the right foot.
Rollins is heading back to Tacoma after working 1 1/3 scoreless innings in Friday’s 8-4 victory over the Red Sox. The Mariners need to clear space for Sampson on their 25-man active roster prior to Saturday’s game.
Sampson, 24, is 7-4 with a 3.25 ERA in 13 starts for the Rainiers. Sampson is a Redmond native who attended Skyline High School and Bellevue Community College. The Mariners acquired him last July from Pittsburgh for lefty J.A. Happ.
Miley’s injury prevented him from facing a former club for the first time in his career. The Mariners obtained him and Aro in a Dec. 7, 2015 trade for right-handed reliever Carson Smith and lefty starter Roenis Elias.
"You always get a little extra adrenaline when you come back to some place you’ve been before," said Miley, who was 11-11 with a 4.46 ERA for the Red Sox. "It would have been my first time doing that. I was looking forward to it.
"I just talked to (Boston right-hander Rick) Porcello. We were going to match up. It’s one of those things. I’m just trying to be smart."
Ironically, Elias made his first start Friday for the Red Sox after being recalled earlier in the day from Triple-A Pawtucket.
Aro, 25, was 2-2 with a 2.45 ERA in 22 games at Tacoma, while Rollins, 26, was 2-0 with a 2.36 ERA in 22 games. The Mariners acquired Rollins from Houston in the December 2014 Rule 5 Draft.
Add second-round pick Joe Rizzo to the Mariners’ list of confirmed signed. Rizzo, a high school third baseman from Oak Hill Va., agreed to a bonus of $1.75 million and will report to Peoria in the Arizona Rookie League.
The Mariners went over the assigned slot value of $1,252,100 to lure Rizzo, 18, away from a collegiate career at South Carolina.
In all, the Mariners have signed 22 of their 40 selections, including 13 of their first 14 picks. The only exception is Oklahoma State shortstop Donnie Walton, a fifth-round pick. Oklahoma State is playing in the College World Series.
The Mariners confirmed signing of third-round pick Bryson Brigman, a shortstop from San Diego. The News Tribune reported Thursday that Brigman had reached agreement on a $700,000 bonus.
Other signings not previously reported: pitcher Thomas Burrows (fourth round), catcher Jason Goldstein (9), pitchers Reggie McClain (13) and Kyle Davis (14), outfielder Dimas Ojeda (17), pitchers Jack Anderson (23) and Paul Covelle (27).
Brigman, Burrows, Goldstein, McClain, Davis, Anderson and Covelle will report to Short-A Everett. Ojeda will join Rizzo at Peoria.
Outfielder Alex Jackson appears to be finding his form at Lo-A Clinton.
Jackson, 20, went 3-for-5 with a homer and four RBIs in Thursday’s 7-6 loss to Kane County (Diamondbacks). He is 9-for-20 in his last five games, which boosted his average to .200 through 26 games.
The Mariners selected Jackson with the sixth overall pick in the 2014 draft, and he entered the season ranked No. 1 in the TNT Top 10 list of the organization’s prospects.
It was 14 years ago Saturday — June 18, 2002 — that the Mariners faced outfielder Ken Griffey Jr. for the first time as an opponent when they beat the Reds 8-1 in Cincinnati.
Griffey went 2-for-3 with a walk. It was the first of his eight career games against the Mariners, and he went 10-for-26 (.385) with three homers and six RBIs in those games.
The Mariners traded Griffey to the Reds on Feb. 10, 2000 with minor-league pitcher Jake Meyer for outfielder Mike Cameron, infielder Antonio Perez and pitcher Mike Cameron.
Griffey will be inducted July 24 into the National Baseball Hall of Fame in Cooperstown, N.Y. He will be the first player inducted primarily for his career accomplishments while playing for the Mariners.
Catcher Chris Iannetta, who started Friday’s game, entered the weekend having logged 452 1/3 defensive innings. That is second among American League catchers to Toronto’s Russell Martin’s 456 innings…this weekend series matches the American League’s two highest-scoring clubs. Boston entered Friday averaging 5.82 runs a game. The Mariners were second at 5.00…Robinson Cano’s career average of .340 at Fenway Park, entering the series, was the highest among active players who have a minimum of 350 plate appearances…first baseman Dae-Ho Lee entered the weekend ranked second among AL rookies in homers (10) and RBIs (27) despite having just 114 at-bats.
The Mariners and Red Sox continue their three-game weekend series at 1:05 p.m. Pacific time Saturday at Fenway Park.
The Mariners are expected to promote right-hander Adrian Sampson from Triple-A Tacoma to replace injured Wade Miley as their starting pitcher. Sampson (7-4 with a 3.25 ERA at Tacoma) will be making his major-league debut.
Boston plans to start right-hander Rick Porcello (7-2, 3.81). The game can be seen on Root Sports Northwest and heard on 710 ESPN.
Bob Dutton: @TNT_Mariners