Right-hander Tyler Thornburg has refused an optional to Triple-A Pawtucket with the Red Sox and is “trending toward being released” by the organization, Rob Bradford of WEEI.com reports (via Twitter). The Red Sox recalled Thornburg’s rehab assignment yesterday, triggering a 48-hour window to either bring him to the big leagues or option him to the minors. As a player with more than five years of MLB service, however, Thornburg has the right to reject a minor league assignment.

Thornburg, 30, has been on the shelf since late May due to a hip impingement. He’s pitched 18 2/3 innings out of the Boston ’pen this year, but despite picking up 22 strikeouts in that time, he’s scuffled to a 7.71 ERA thanks to the 10 walks and four homers he’s allowed.

Injuries have decimated Thornburg’s tenure with the Red Sox since Boston acquired him from the Brewers in the December 2016 trade that sent Travis Shaw to Milwaukee. At the time, Thornburg was coming off an excellent season, having given the Brewers 67 innings of 2.15 ERA ball with a gaudy 90-to-25 K/BB ratio. Controllable for another three seasons, Thornburg looked like a potential long-term late-inning option in the Boston relief corps.