Today is the 40th anniversary of the Pine Tar Game, in which George Brett temporarily lost a home run because the pine tar on his bat was too high toward the barrel. The announcers discussed this during the Sunday Night Baseball broadcast, but they left out a reason the Yankees thought they could get Brett. Years before, Lou Piniella lost a hit (I believe it was in Minnesota) because the Twins complained he had too much pine tar on the bat. So there was precedent for taking away a hit, and the Yankees had suffered it. (I watched both games, so when they took away Brett’s homer, I was not surprised.)
The announcers did make a point that I hadn’t heard before. Eduardo Perez noted that pine tar was used to hide alterations to the bat that would help with putting spin the batter ball. Not:
The rulebook provision was meant to avoid dirtying too many baseballs, not to affect the outcome of a play or game.
ESPN.com
I suspect MLB did not want to promote the idea that batters were cheating, just like they underplayed steroid use for years. Dirty baseball strike me as a convenient cover story.

