During Winter Meetings, teams were informed not to allow personalized decals on their players' bats, CSN Bay Area Giants insider Alex Pavlovic reported on Friday.
MLB's new rule will spell the end to Matt Duffy's signature "Duffman" decal, which received national attention during his rookie season and spring training last year.
"I watched the Simpsons growing up," Duffy told Amy Gutierrez of CSN Bay Area in a 2014 interview (video above). "I was actually almost gonna be Duffman for Halloween one year, but it was just a ton of work."
A few other Giants players also had their own decals last year, according to Pavlovic, who compared the MLB's decision to something the NFL would do.
For years, the NFL has been referred to as the "no fun league" due to its strict measures on player celebrations and on-field attire.