Meanwhile, the Rangers tried to plug the fifth slot in their rotation with a three-way trade that brought left-hander John Koronka to Texas.
Rangers medical personnel met with Eaton on Friday night, but team spokesman Gregg Elkin said that "fact finding" on the optimum way to treat Eaton's injured right middle finger had not been completed.
One option is surgery. The other is rest and rehabilitation. Eaton said Thursday that he expected to be out for the first three months of the season, although manager Buck Showalter said prior to Friday night's exhibition game against the Florida Marlins that Eaton might not be out that long.
"I never said it was three months," Showalter said. "It was something everybody jumped all over. They called it vague yesterday. I wanted to be cautious until all the opinions were in. If we're going to opt for surgery, we want to do that as early as possible."
Eaton met with Showalter and team physician Dr. Keith Meister on Friday, with no conclusions. He will certainly miss his first start for the Rangers Tuesday night against the Boston Red Sox, and probably several more. Right-hander Kevin Millwood will start Texas' home opener on Monday against the Red Sox.
Right-hander Vicente Padilla moves up to become the No. 2 starter in place of Eaton, with Kameron Loe sliding up from the fourth to the third slot and knuckleballer R.A. Dickey advancing from the fifth to the fourth rotation spot.
The Rangers then made a series of moves to solidify the rotation in the wake of Eaton's injury. The Rangers sent right-hander Juan Dominguez, who was 4-6 with a 4.22 ERA in 22 games for the Rangers last season, to the Oakland A's for Minor League left-hander John Rheinecker and infielder Freddie Bynam.
The Rangers then dealt Bynam to the Cubs in exchange for John Koronka, another left-hander and a former Texas farmhand. The Rangers also will receive either cash or a player to be named from the Cubs.
Koronka was 1-2 with a 7.47 ERA in four games for Chicago last season and was 9-11 with a 4.24 ERA in 23 games for the Iowa Cubs, Chicago's Triple-A affiliate.
The Cubs were grooming Koronka to pitch out of the bullpen, where he was 1-0 with a 3.75 ERA this spring, but the Rangers will try him first as a starter.
Koronka will throw a simulated game on Sunday to build arm strength and get him ready to start again.
"We want to get his pitch count up, stretch him out and get him into the mix," general manager Jon Daniels said. "He wants to start and we got him to start."
Daniels said Koronka has developed a slider, giving him three pitches. As for Eaton, he was in an upbeat mood prior to the game and Showalter is trying to take the high road and not dwell on the rotation setback.
"I look at it real positive," Showalter said. "Because we had a guy get hurt toward the end of the spring, it's not going to be this gloom and doom people want to get involved with. Adam's in a lot better frame of mind. He hasn't had near the swelling or the soreness we might have expected."
Final roster taking shape: The Rangers placed four players on the 15-day disabled list on Friday as they moved closer to Saturday's 11 p.m. CT deadline to reach the 25-man limit.
RHP Josh Rupe (elbow inflammation), infielder Marshall McDougall (recovering from left wrist surgery), LHP C.J. Wilson (right hamstring strain), and RHP Frankie Francisco (recovering from Tommy John ligament transplant surgery on his right elbow) were all sent to the DL.
All four moves are retroactive to March 24 and they are all eligible to be activated on April 8.
Also expected to be moved to the DL are Eaton and outfielder Gary Matthews Jr. (strained rib cage). As a result, Showalter wasn't prepared to declare his opening-day 25-man roster on Friday night.
"We're not ready to finalize it now," Showalter said. The manager is also trying to determine what his Opening Day lineup will be. The infield, made up of Mark Teixeira, Ian Kinsler, Michael Young and Hank Blalock, is set. So are Millwood at the top of the rotation and catcher Rod Barajas.
But Showalter wants to wait before announcing his starting outfield until he knows the health status of Brad Wilkerson and Laynce Nix (sore shoulders).
A very major Minor League park: Rangers players were impressed with Dr Pepper/Seven Up Ballpark, site of Friday night's exhibition game against the Marlins.
The park is the home of Texas' Double-A affiliate, the Frisco RoughRiders, and is considered one of the most impressive Minor League ballparks in the country.
"Minor League parks were never like this," Showalter said.
Quick hits: The Rangers waived RHP John Wasdin earlier this week. Wasdin later agreed to a Minor League contract. Showalter said Wasdin will open the season in the rotation at Triple-A Oklahoma. ... The club still has a few standing room tickets left for Monday's home opener against the Red Sox. ... Arena Media Networks (AMN) and the Rangers announced a partnership to launch a new, high-tech digital media network to provide up-to-the-minute information and programming designed to enhance the fan experience during the game. Co-CEO of AMN Tom Kiernan and Rangers president Jeff Cogen made the joint announcement. AMN is currently installing large high-definition video displays near high traffic, prominent locations such as concession stands and box office windows where it will broadcast full-motion video programming, advertising content, and sports team and event information. In addition, the network offers a programming mix of sports scores distributed via a live feed from ESPN Sportsticker, entertainment news, team highlights and trivia, weather forecasts, financial market updates, and other programming. The network is scheduled to launch during the Rangers home opener.
Ken Sins is a contributor for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.