McMullen will begin rookie league play on Thursday, and that will continue until Aug. 31.
"At that point, I'll come back to Chickasha," he said. "There's an instructional camp in October back out in Arizona that I'll go to if I'm invited. If not, I won't go back until February and get a workout schedule to keep in shape."
In the meantime, McMullen keeps tabs on former Drover teammate and fellow prospect Brian Vigo, who was selected by the St. Louis Cardinals last week as a free agent.
"I'm very excited for him," McMullen said. "We stay in touch. It's good to have someone to talk to that's going through the same thing. It's also pretty cool to see how different teams are organized."