bowling fanatics

[Mr.WeakTight]

i bowl like once a year. i took my kids bumper bowling. the guy next to us was mr uber bowler. had 9 of his own bowling balls. threw it like a pro with a curve and usually made a strike &/or picked up his spare. after about every ball, he'd take out some kind of piece of tape from inside one of the finger holes and move it.

anyone know what he was doing with that tape? why would a guy have 9 balls? was he likely a pro?