"It has been pretty vague," Griffin said. "I'm just trying to get though the next few days and see what happens. It's part of the job, so I just got to sit tight and just be ready to go whenever they ask me to."
Griffin threw a bullpen session Saturday at Globe Life Park, but he hasn't been told by the club if he's the No. 5 starter or not.
"He was assigned to Round Rock," Texas manager Jeff Banister said. "You guys can disseminate what you need to. I've had multiple conversations with Mr. Griffin about all the options going forward."
Texas set its Opening Day roster Sunday by putting right-handed pitchers Yu Darvish and Luke Jackson, catcher Chris Gimenez and outfielder Josh Hamilton on the 15-day disabled list.
• Rangers' depth chart
The Rangers will open the season with eight relievers, but one will be sent down Friday to make room for the No. 5 starter.
Griffin appeared to have won that battle over Chi Chi Gonzalez, Nick Martinez and Cesar Ramos, each of whom will open the season in the Round Rock rotation. The club also released Jeremy Guthrie, who was vying for the job.
Griffin, who hasn't pitched in the Majors since 2013 because of elbow surgery, was 1-2 with a 6.00 ERA in six spring appearances with the Rangers. Opponents hit .286 against him over 18 innings, but he struck out 19 and walked just two.
Griffin thinks those numbers should be good enough to get him a Friday start.
"I'm just being hopeful," Griffin said. "I'm trying not to assume anything. It just gives them time to do what they want to do to set up the team they want. It's just of the deal, part of the job. I'm just taking care of my business every day and being ready to go when they give me the opportunity."
In 2013, his only full season in the Majors, Griffin went 14-10 with a 3.83 ERA for Oakland. He made 32 starts and pitched 200 innings. Griffin didn't pitch at all in '14 and was limited to 14 1/3 innings in the Minors in '15 before being designated for assignment by the A's last November.
Anthony Andro is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.