Kimbrel injured his knee while shagging during batting practice prior to Friday's game.
"I was just in the outfield during BP and took a step for a ball that was a ground ball that was hit. I took a step, heard a pop and didn't think it was anything serious until I got in, evaluated it, got the MRI, saw what it was," Kimbrel said on Saturday. "Now, it's taking steps to get it better so I can get back out on the field."
This is the first time in the 28-year-old's seven big league seasons that he has been placed on the DL. Kimbrel has 17 saves and a 3.55 ERA this season. He will miss Tuesday's All-Star Game presented by MasterCard. Blue Jays right-hander Aaron Sanchez took his place on the American League roster.
Red Sox manager John Farrell said the recovery time for each player is different, but Kimbrel is hoping to feel better sooner rather than later.
"It's obviously frustrating," Kimbrel said. "I'm kind of glad it's nothing too serious. It's something we can go in and get it scoped out, get it cleaned up. The timetable they're saying [is] 3-6 weeks. Let's hope it's more on the three weeks' side if not a little faster than that."
Following the MRI, Kimbrel was initially ready to play through the pain. But disregarding the injury would involve changing pitching mechanics or putting more strain on a healthy arm, two things Kimbrel wants to avoid.
Farrell said Kimbrel will return to the mound when he's ready to pitch against Major League hitters. Along the same lines, Kimbrel does not want to return to the mound until his knee feels comfortable and fully recovered. But once the rehab is finished, Kimbrel expects to return to the mound with full strength.
Neither Kimbrel nor his manager are looking to put an end to pitchers shagging balls during batting practice.
"Honestly, this is an anomaly," Farrell said. "This is what our players go through normally day-in, day-out, traditionally in the game. We can't put guys in bubbles. And yet, you get a little bit of a change in direction, and this is what happens. Unfortunately, in this case, Craig's case, we're going to miss him for a little bit."
• Right-hander Noe Ramirez was called up from Triple-A Pawtucket on Saturday. The 26-year-old has made 17 appearances with Pawtucket this year, recording three saves and going 1-3 with a 2.45 ERA.
• Utility man Michael Martinez was acquired from Cleveland on Friday in exchange for cash considerations. Martinez hit .283 with three doubles and a home run in 32 games for the Indians this season. He made five starts in right field, three in center, two at second base, one at third and one in left field.
• Infielder Marco Hernandez was optioned to Pawtucket on Saturday. The 23-year-old appeared in 29 games over two stints with the Red Sox during his first Major League season, batting .295 with one double, one home run, five RBIs and seven runs.