The Mariners are putting left-hander James Paxton back on the shelf after a magnetic resonance imaging (MRI) exam revealed inflammation in his throwing shoulder.
Paxton will do no throwing activities until the inflammation dissipates, which is expected to take at least five-to-seven days.
The announcement came three days after Paxton threw 62 pitches in a rehab start for Triple-A Tacoma, which marked his first game action since suffering a strained back muscle in an April 8 start against the Angels.
The news represents something of a surprise. Paxton reported some minor soreness in his triceps after Saturday’s game.
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The Mariners also reported right-hander Stephen Pryor will be placed on the seven-day disabled list for minor-league players after being diagnosed with a shoulder impingement.
Pryor is recovering from a torn back muscle that sidelined him for nearly all of last season. He has allowed 16 runs and 20 hits in 18 innings this season in 16 appearances with 16 walks and 13 strikeouts.
Club officials said Pryor is likely to miss at least a week.
Paxton’s latest ailment shifts the Mariners’ short-term rehab focus to right-hander Taijuan Walker, who is scheduled to begin a minor-league assignment Wednesday at Tacoma in his recovery from shoulder soreness.
Walker is slotted for 70-75 pitches against Salt Lake (Angels) at Cheney Stadium. His shoulder problems surfaced in February and returned in mid-April when he appeared poised to rejoin the rotation after two rehab starts.
“Everything feels great,” he said.
Then again, Paxton reported no problems in his recovery from a strained left latissimus dorsi muscle prior to (or after) his Saturday rehab start for the Rainiers.
Paxton’s latest injury seems to ensure at least one more start for right-hander Brandon Maurer, who is 1-3 with a 6.99 ERA in six starts. Paxton had been viewed as a possible replacement before his latest problem.