Nationals center fielder Adam Eaton, who was carried off the field Friday, has a torn left ACL and will not play again this season, general manager Mike Rizzo told reporters Sunday.

Rizzo also revealed that Eaton had suffered a torn meniscus and a high ankle sprain.

No surgery has been scheduled, Rizzo told reporters, adding that he expects Eaton to miss six to nine months.

Shelby Miller has decided to undergo Tommy John surgery.

Miller, who was also diagnosed with a flexor strain, had been evaluating his options, which included trying to rehab the injury through non-surgical options.

"It's the best decision I think we could make," Miller said

Miller is 2-2 with a 4.09 ERA in four starts this season. He went 3-12 with a 6.15 ERA in 2016.

Sandy Alderson said Saturday that it was unusual for a player to refuse an MRI, as Noah Syndergaard did Friday, but said, "I can't strap him down and throw him in the tube."

Syndergaard is scheduled to start for the New York Mets on Sunday after he was pulled from his start Thursday because of biceps and shoulder discomfort.

Syndergaard is 1-1 with a 1.73 ERA in four starts.

"I think I know my body best," Syndergaard told reporters. "I'm pretty in tune with my body, and that's exactly why I refused to take the MRI."

Adam Eaton has been placed on the disabled list by the Washington Nationals with a left knee strain.

Eaton suffered the injury in the 9th inning of Friday's loss.

"Nothing yet," Dusty Baker said Saturday. "He had to be driven home after last night so we're waiting from the MRI because it's not that easy. Not that many people working on Saturdays. Hopefully it's not as serious as looked."

Shelby Miller has been diagnosed with a flexor strain and partially torn ulnar collateral ligament.

Miller is considering his options, including Tommy John surgery and is expected to decide soon.

The non-surgical route for Miller would include a platelet-rich plasma injection or stem cell treatment.

Major League Baseball changed the 15-day disabled list to a 10-day option as part of the new collective bargaining agreement agreed to in December.

Thus far, teams have used the disabled list more often given the shorter option.

165 players appeared on the 10-day DL in the season's first 25 days, according to Major League Baseball. That's a 12 percent increase over the same span from 2013 to 2016.

"You see this all the time: They say an injury is day-to-day," Pete Mackanin said. "Then two days turns into four days and four days turns into six. Well, if that's the case, you might as well put him on the DL [right away] rather than play short for a week."

The Los Angeles Dodgers have had the most DL stints this season with 12.

Shelby Miller's MRI is being sent to Dr. James Andrews for a third opinion.

Miller was asked directly if the first two readings of his MRI showed a torn ulnar collateral ligament.

"They see something in there," Miller said to reporters. "They haven't given me specifics yet, exactly what it is or how we're going to handle it or what we're going to do to fix it."

The Arizona Diamondbacks have downplayed the injury thus far.

"It's part of the plan that we had talked about all along where we were going to have this group look at it and come together and get as much information as we possibly could, and pass it along to Shelby and figure out what the best game plan is," Torey Lovullo said.

Eric Thames left Wednesday's game against the Cincinnati Reds in the top of the eighth inning with tightness in his left hamstring.

Craig Counsell said after the Milwaukee Brewers' victory that the injury is "not a big deal."

"It just kind of tightened up over the day," Counsell said. "It is really the on-base stuff. He's just been on-base a whole bunch, running the bases, scoring from first, so just a whole bunch of baserunning."

Thames leads all of baseball with 11 home runs.

Felix Hernandez was set to return to Seattle to have a stiff right shoulder checked by Mariners doctors after he lasted only two innings in his start Tuesday night.

Hernandez allowed four runs and six hits in the appearance.

There was no injury announcement after he was removed from the game, but afterward, Scott Servais said the right-hander was dealing with stiffness.

"He had some stiffness in his shoulder going out for the second inning, but there wasn't any pain," Servais said. "He said it was more like a dead arm, but there's obviously some concern when you are talking about a pitcher's shoulder. He's been a horse for us, but we have to get this checked out."

Hernandez has made at least 30 starts for the Mariners every season from 2006 through 2015.

"We should know a lot more in a couple days," Servais said. "At this point, it's just a dead arm."

Madison Bumgarner will not require surgery on his sprained pitching shoulder and is expected to be out for two months.

The left-hander bruised ribs and sprained the AC joint in his pitching shoulder in a dirt bike accident during last Thursday's off day in Colorado.

"Our focus is on getting him healthy," Bobby Evans said.

Bumgarner will wear a sling on his pitching arm for at least another week and is likely to miss approximately two months.