DENVER — The disappointment radiated from Clayton Kershaw as he trudged into the Los Angeles Dodgers clubhouse Thursday afternoon. Soreness in his left arm had sidelined him for a month. In his first start back from the disabled list, discomfort in his back reduced his fastball to 86 mph and truncated his outing to five innings.

Closer Kenley Jansen could see the anger and sadness in Kershaw’s body language as he entered the room.

“He did everything he could do to come back, and now his back gave out on him again,” Jansen said before Friday’s series opener against the Colorado Rockies at Coors Field. “It takes the air out of you.”

An MRI taken Friday confirmed the fears espoused by the Dodgers a day earlier. For the third consecutive season, the team placed Kershaw on the 10-day disabled list with a back injury. The official diagnosis was a lower back strain. The familiarity of the setback did not reduce its sting.

Kershaw suffered a similar injury in 2017. He missed five weeks. Manager Dave Roberts described the latest iteration as “comparable to last year” and suggested Kershaw would miss at least a month. Kershaw remained in Los Angeles after receiving a pain-killing epidural injection to quell the inflammation in his back.

Roberts said the examination revealed no damage to the disks in Kershaw’s back. A herniated disk in 2016 sidelined Kershaw for 10 weeks and sounded the first alarm about his long-term viability. During his time away that summer, Kershaw reshaped his workout routines and fixated on stabilizing his back and core muscles. The preventative care could not protect him from the attrition of pitching, which had already caused a case of biceps tendinitis in May.

“No one works harder,” Roberts said. “No one prepares better. What can we do? I don’t know. I think that’s past my intelligence. I don’t have any remedies, or even any thoughts.”

The injection will limit Kershaw for a few days as the medical staff waits for the treatment to take hold, Roberts said. The team hoped he would benefit from rest. Roberts acknowledged Kershaw would bristle at any restrictions and attempt to expedite his return to the mound.

He took a similar tack after experiencing soreness in his shoulder in early May. Kershaw waited a couple of days before throwing again, rebuilding arm strength only to have his back betray him Thursday.

“It’s tough because of his work ethic and the amount of time that he spends on being right,” third baseman Justin Turner said. “It almost doesn’t make sense that this stuff is popping up on him.”

His injury occurred at a strange time for the Dodgers’ starting staff. The team is operating with four members of the opening day rotation on the disabled list. With the injuries piling up, the team chose to start reliever Scott Alexander on Friday against the Rockies, with rookie Dennis Santana going 3[2/3] innings to get the win.

Yet starting pitching has been the team’s strength. The group entered Friday with a 3.28 ERA, fourth-best in the majors. Walker Buehler and Ross Stripling have been excellent. The team has shown an ability to survive Kershaw’s absences in the past.

“It absolutely won’t destroy us,” Roberts said. “It speaks to the guys in the clubhouse, the character, the relentlessness. It’s not ideal, losing four-fifths of your starting rotation. But we have guys we can plug in.”

Kenta Maeda could return from his hip strain later this month. Hyun-Jin Ryu will be out until after the All-Star break as his torn groin muscle heals.

Beset by blisters, Rich Hill petitioned Major League Baseball officials Joe Torre and Peter Woodfork to allow him to pitch with a bandage on his left middle finger. Hill was informed he will not be allowed to do so in 2018, but he can petition baseball’s rules committee this winter to make the practice legal in the future.

Until then, Hill will try to heal the blister with laser therapy. He played catch without tape on his finger Friday. He plans to throw a bullpen session without any tape Saturday and face hitters next week in a simulated outing while the team is in Pittsburgh.

Kershaw will not join his team in the Steel City. It was there, in 2016, when the severity of his back trouble first leaked into public view. His career has never been the same.

The 2018 season has been more unkind to Kershaw than most. His average fastball velocity fell from 92.7 in 2017 to 90.9 mph this year, according to FanGraphs. He gave up seven homers in eight starts. His 2.76 ERA, while still excellent, is his highest since 2010.

Kershaw can opt out of the final two seasons of his seven-year, $215-million contract this winter. He has not revealed his intention, although the industry expected him to elect free agency and join a class of superstars that includes Bryce Harper and Manny Machado.

The concern about Kershaw’s back could sway his decision. It could also temper the zeal with which the Dodgers pursue him, should Kershaw opt out.

All that will be decided in the future. In the present, the Dodgers mourned yet another ailment for their ace. Injuries formed bookends to his May. After his start May 1, the soreness in his shoulder forced him onto the disabled list. The instability of his back meant his comeback lasted only five innings.

To Jansen and others, the outcome did not seem fair.

“You’re talking about a guy who does everything right,” Jansen said. “Eating right. Taking care of his body. He outworks everybody. And still stuff doesn’t go his way. You can’t control stuff like that. It’s frustrating.”