AFAIK, it’s just a one-time deal for the Japan games. The Mets and Cubs sported ads back when they played there.
Soccer teams throughout the world have worn ads on their uniforms for years and yet people don’t seem to have any hard time rooting for the Man U Vodafones.
I am 100% positive MLB teams will wear ads on their uniforms. I’d guess it will begin within the next ten years or so. My guess is that a corporation will buy “naming rights” to a team’s uniform. The New York Citibank Yankees.
I guess MLB can do whatever they want, since it’s their rulebook, but that’s what it says. I don’t doubt that somewhere down the line, there will be advertisements on uniforms, but not to NASCAR’s level. They make too much money off of merchandising sales to do that, I would think. Who would buy a Viagra/Tide/Budweiser A-Rod jersey?