"After I kind of thought about it and talked to some doctors, I just kind of looked at the field a little bit more," Cobb said. "I've seen guys go down this road and feel like it's the best decision to go ahead and get the surgery done.
"It was a tough decision, because you want to hold onto every hope that you can pitch this year and contribute. I think not only for my own future, but going into next year, for the team next year, [it's] better not to waste any more time."
Cobb expects to have the surgery performed by Dr. James Andrews on Thursday. Based on that date and the normal recovery from Tommy John surgery -- 14 to 15 months -- the Rays are hopeful he can be back by around September 2016.
Initially, Cobb's injury was diagnosed as right forearm tendinitis. But after begining rehab, Cobb had a setback on Sunday. That prompted an arthrogram, which revealed a bigger problem than the first diagnosis.
"It's a significant tear," Cobb said. "I've had obviously a few opinions. I've had multiple doctors say it's a full tear. It's more significant than I think we originally thought. It doesn't seem to be a rehab type of situation."
Cobb noted that seeing other pitchers take the rehab route and eventually have to have surgery played a part in his decision.
"It's better to just go ahead and do it, not waste any more time," Cobb said.
In addition, seeing how well teammate, and friend, Matt Moore has been doing in his rehab from Tommy John surgery also was a integral to his decision.
Moore "looks great," Cobb said. "Looking and watching this month and a half when I've stayed back every day with him and watched his rehab process go really full out in live BP ... and see how the ball's been coming out of his hand. And seeing how he's been able to manipulate the ball, meaning his feel of pitching is there too, which is probably the most relateable to me.
"I have to be able to manipulate the ball and I feel like he's doing it the best he's ever done in his career. It's easier for me to go ahead and see that out of him and go ahead and do the surgery without a whole lot of worry."
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.