Dodgers pitcher Alex Wood has been shut down from throwing for four weeks. (Getty Images)

CHICAGO — Alex Wood‘s MRI today revealed a posterior impingement in his elbow, the Dodgers announced. The left-hander will get approximately four weeks of rest and be re-evaluated at that time.

That’s bad news for the Dodgers, who will be without a pitcher whose solid performance in May (3.18 ERA, 41 strikeouts in 28 ⅓ innings) was second only to Clayton Kershaw among starting pitchers. Wood had been scheduled to throw a bullpen session Thursday at Wrigley Field. When his pain didn’t go away Tuesday, the day after his 5-inning start against the Cubs, Wood was placed on the 15-day disabled list instead.

For Wood, the news could have been worse: The source of his elbow pain is not related to a damaged ligament.

A torn ulnar collateral ligament would almost certainly lead to a recommendation of Tommy John surgery. The 25-year-old has had the procedure once before, following his senior year of high school. The prognosis for multiple Tommy John recipients, when comparing their post-surgery performance to their pre-surgery performance, is generally bleak.

Still, whatever is causing Wood’s elbow pain is bad enough that he will need an extended period of rest. And “rest” is the most vague cure of all, in that it comes with little certainty. Wood might not be cleared to resume a throwing program once his four weeks are up and, if he is, there’s no telling if he’ll still be affected by whatever is causing the pain.

Wood had seen an increase in velocity in all of his pitches this season compared to 2015, when he was traded to the Dodgers ahead of the Aug. 1 deadline. His fastball, which regularly maxed out in the 89-92 mph range as a Dodger last year, was clocked at 93 and even 94 in games this year.

The Dodgers recalled Julio Urias to take Wood’s place on the active roster Monday. He’ll go into a starting rotation that also includes Kershaw, Scott Kazmir, Kenta Maeda and Mike Bolsinger.