Beavan, who grew up in nearby Irving, Texas, has been rooting for the Rangers since he was four. Beavan threw 66 innings with 124 strikeouts and a 0.23 ERA his senior season with Irving High School.
Rangers general manager Jon Daniels repeatedly said he was "optimistic" before Tuesday's game against Kansas City, but needed the next couple of hours to finalize the contract. The Rangers sent representatives to Beavan's house, where he signed. Beavan did have to cut a golf outing short in order to finalize the contract.
"I always felt we were going to get it done," Daniels said. "I never felt Blake was going to go to school. I expected that we'd get him sign and I'm happy he's under contract. The only negative is he's going to miss a whole summer of playing.
"I had a sense early on this would drag out," Daniel added.
Over the summer, Beavan has been working out and throwing on the side, facing no competition.
"Not pitching against any hitters got me worked up, and I was ready to go and sign," Beavan said.
When Beavan reports to Arizona on Thursday, Daniels wants him to get assimilated with the coaching staff and begin working out. Beavan will then return home to Irving for a couple of weeks before going to the instructional league.
Beavan, a power pitcher with a fastball that has clocked at 98 mph, could not place a timetable on when he expects to be in the Major Leagues.
"It depends how hard I work in order to get there," Beavan said. "Having that mindset and keep working with my slider and, hopefully, making my changeup a dominant third pitch."
The Rangers also signed their 13th-round selection, Kyle Ocampo, a right-handed pitcher from Riverside, Calif., on Tuesday. Ocampo was 8-0 with a 1.83 ERA over 57 1/3 innings with Riverside Poly High School.
The Rangers are still expected to sign Julio Borbon (35th overall) and Neil Ramirez (44th overall). Daniels is hopeful the deals will be completed by the Wednesday 10:59 CT deadline.
The Rangers have now signed 28 of their 54 draft picks.