Ellsbury, who missed 95 games in two other DL stints this season, injured the area where he fractured five ribs in an April collision with third baseman Adrian Beltre. Ellsbury was injured Friday night in a first-inning collision with Rangers pitcher Tommy Hunter.
Ellsbury flew to Boston on Saturday morning for an MRI and a CT scan. Red Sox manager Terry Francona said the results showed some edema to the soft tissue in the same area, which is suggesting new trauma. He said there's a faint line at the fracture site, which could suggest incomplete healing.
"You just have to go on the symptoms and [Ellsbury] said it was worse than in Tampa, so we knew this was a DL [move]," Francona said. "So now that's he on the DL, we'll try to find out, 'What do we do?'"
Ellsbury went on the DL for the second time this season in May after feeling pain taking swings in the batting cage before a game in Tampa. He finally returned on Aug. 4 and had been struggling before turning things around a bit this week. He stole five bases in five games, including four Monday against the Yankees.
Francona said it wasn't known yet whether Ellsbury would fly to California to visit Dr. Lewis Yocum. When asked if this latest injury could end Ellsbury's already-shortened season, Francona said only that Ellsbury would be out for 15 days.
Francona said that Ellsbury fought to stay in Friday night's 10-9 loss to the Rangers.
"It was pretty obvious to me he was hurting," Francona said. "He didn't want to come out. I'm glad I took him out now. Obviously he was hurt. If he had gotten hurt worse, I mean, that doesn't help anybody."