Last of the pine-tar posts. But this seems pretty persuasive:

E-mail:

Subject: Wrong on Pine Tar
Rich-
Please see [this link]. I have known this since the
Pine Tar incident in 1983, as my friend had just gone
to camp to try and become an MLB umpire.
MacPhail really sandbagged the both Yankees and his
umpires with his decision. Brett had actually broken 2
existing rules:
=> 1.10c, which regulated the permissible amount of
Pine Tar
and
=> 6.06d, which defined the penalties for use of an
illegal bat, which include being called out and being
ejected.
Whether it was the “spirit” or not, it was in the
written rules. Billy Martin and the umps were actually
“Strict Contructionists,” while Brettwas the
beneficiary of an “emanating penumbra.