What Yankees think of Justus Sheffield’s progress as a reliever

Top pitching prospect Justus Sheffield likely will be joining the Yankees in September.

NEW YORK — Yankees No. 1 pitching prospect Justus Sheffield’s first week as a reliever included some good and bad.

The 22-year-old left-hander allowed a run on two hits over two innings in his first relief outing pitching for Triple Scranton/Wilkes-Barre on Aug. 21, then gave up one run on three hits over three innings in his second four days later.

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“He’s had two bullpen outings now where he’s gone a couple of innings (and) they’ve been OK,” Yankees manager Aaron Boone said Tuesday. “I think we want to see him get at least another one down there.”

If Sheffield fares well in his next one or two bullpen assignments, he’ll probably get his first big-league call-up within the next week to take on a late-season role as long reliever/situational left-hander. Big-league rosters can expand from 25 players on Sept. 1.

“That’s one of the conversations we’ve been having,” Boone said. “I don’t think anything’s been decided for sure yet but something we’re talking about certainly in the coming days.”

Sheffield isn’t currently on the 40-man roster, but he can be added after August by taking a postseason eligibility spot away from a Yankees pitcher who has been on the 60-day disabled list at least 60 days. The Yanks have two who meet that criteria, right-hander reliever Ben Heller and lefty starter Jordan Montgomery.

Whatever Sheffield does this season, he’s expected to return to starting in 2019. Depending on what the Yanks due in the offseason, he could go into spring training in the running for a rotation spot.

Sheffield is 6-6 with a 2.56 ERA this season in 23 games, 20 as a starter, with 119 strikeouts in 112 2/3 innings, including 5-4 with a 2.66 ERA in 18 outings since being promoted from Double-A Trenton to Triple-A Scranton/Wilkes-Barre on May 4.

Randy Miller may be reached at [email protected]. Follow him on Twitter @RandyJMiller. Find NJ.com on Facebook.