Not totally sure on this Tone, but I've narrowed it down to (5) possible reasons:
1.) He decided that he'd rather be playing guitar for those 3-5 minutes that he'd been fussing with his hair in the morning (like he needs the practice!)
2.) The heat rising up off of the fretboard from his furious solos was causing him to sweat profusely, and in turn, wet hair to stick to his face ~ which he didn't like. The new, aerodynamic doo solved that problem.
3.) Joe's always been a big fan of the hit 70's cop show Kojak, starring Telly Savalas. Joe uses a chrome Ibanez RG custom instead of a lollipop for his signature "schtick". Hey, who loves ya' baby?
4.) His wife digs the look. I mean really digs the look.
5.) He's an avid hat-wearer, and hats just seem to fit better without any hair.
There it is. I'm tapped. Anybody know the real reason?