Frisco's season ended Saturday night with a Game 4 loss to Springfield in the Texas League championship series.
Font had a 3.00 ERA in 10 relief outings in Frisco. Reports are good on his velocity, and he's throwing strikes and has an improved changeup. Plus he's in better condition since Spring Training, when he was coming off of Tommy John surgery.
"The season has done him well," Rangers manager Ron Washington said. "He looks good. We'll start him out in a non-taxing situation and just ask him to get outs."
Grimm made his Major League debut with the Rangers earlier this season -- he made three starts. He had a 2.81 ERA with Frisco and Triple-A Round Rock. Grimm will be used for multiple innings if needed out of the bullpen.
Both pitchers are on the Rangers' 40-man roster.