Boesch visited with hand specialist Dr. Tom Graham again on Thursday morning for an MRI, which backed up the X-rays taken on Wednesday morning.
"We have to get the swelling down, [though] we didn't have a lot of swelling," Kevin Rand, head athletic trainer, said.
From there, Rand continued, the team's medical staff will work to get range of motion back in the thumb, which Boesch needs for bat control. Since the injury is to his non-throwing hand and the bottom hand of his batting grip, he can play with less range in it rather than if the sprain was his left thumb.
Boesch sounds as though he would like to push it once the swelling is down.
"It feels a lot better today, a lot less swollen, in my opinion," Boesch said. "I'm cautiously optimistic that I'll be in the lineup a lot sooner than probably the doctor I just saw would expect me to be. I talked to [manager Jim Leyland]. It's all about how it feels. It's not about what anyone says. It feels better."
Boesch wouldn't eliminate the possibility that he could play on Friday in Baltimore if the swelling is down, yet he admitted there's a good chance that he won't pick up a bat that day.
"As soon as I can have some movement in my thumb to where I can feel like I can grip a bat and swing, then I'll be trying to press the issue and get back out there," he said.
Ryan Raburn started in Boesch's place on Thursday, batting second and playing left field against Cleveland's Fausto Carmona.