It's purely a musical composition, and Webb plays all the instruments -- lead and bass guitar, keyboards and drums.
The song doesn't have a title, but Webb plans on making it his walk-out music when he enters games at Marlins Park.
As far as Webb knows, no player in the league has composed his own walk-out music. For relievers, the songs last roughly 90 seconds as they warm up.
"About three weeks ago, I was sitting in the bullpen," Webb said. "Out of nowhere I got this little rhythm in my head. I went home and put it into GarageBand, and worked off of it. Eventually, I made an entire song out of it. I never thought I could do that."
GarageBand is program that allows users to play and record music.
Webb makes it clear his composition is far from professionally done.
"For recording it into my computer, it sounds pretty good," he said. "It's not like a professional recording or anything or like."
Webb's current walk-out song is Hysteria by Muse.
Music and drawing, Webb admits, were never his strong suits. But during his second season of professional baseball, he started playing guitar. From there, he picked up playing the piano and drums.
"I've played very, very amateur guitar for a while," he said. "It's just a hobby that I do during the season, even in the offseason.
"I think it sounds pretty cool. I hope people like it. Maybe I'll have a hobby for the offseason and write a couple of songs."