Kershaw is on the disabled list with what the Dodgers say is inflammation in a back muscle. Padres pitcher Andrew Cashner, who spent two months on the disabled list, said his injury also involved a strained lat muscle.
"I think mine was more serious than his," Cashner said.
Still, Cashner's experience could indicate Kershaw might not regain his Cy Young Award form for some time after he is activated.
Neither Kershaw nor the Dodgers have said exactly how the pitcher suffered the injury. Cashner said he knew exactly when his injury happened.
"It was just one pitch," he said. "I felt a grab. I definitely knew something was wrong. I threw a warmup pitch and it kind of yanked."
That was July 3, 2012. He returned Sept. 1, after what he called a "very slow" recovery process.
"There's nothing you can do," Cashner said. "There's no rehab. It's just rest. It's a very frustrating injury."
When he returned, Cashner said, his fastball velocity was 91-92 mph. His career average is 95 mph, according to Fangraphs.
"It took me seven months before it felt right," he said.