It seems that pretty much every pitcher uses some type of foreign substance to give himself an advantage. Clearly, the rule that forbids foreign substances is not being enforced. If MLB doesn't want to enforce the rule, then why even have it? They need to either enforce it consistently, or do away with it.
If it's really a safety concern, then MLB should approve a few substances that give the pitcher a better grip, but don't otherwise give the pitcher an advantage. Then, if a pitcher is caught using anything else, whether it's blatant or not, he should be tossed.