Frisco's season ended Saturday night with a Game 4 loss to Springfield in the Texas League Championship Series.
The hard-throwing Font had a 3.00 ERA in 10 relief outings in Frisco. Grimm made his Major League debut with the Rangers earlier this season, when he made three starts. He had a 2.81 ERA with Frisco and Triple-A Round Rock in the Minor Leagues.
Both pitchers are on the Rangers' 40-man roster.
Todd Wills is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.