it's understood to be a gray area. you're not supposed to be throwing spitballs, true, but batters aren't necessarily unhappy if pitchers have more control and

it's understood to be a gray area. you're not supposed to be throwing spitballs, true, but batters aren't necessarily unhappy if pitchers have more control and are less likely to hit them in the head. the players also aren't necessarily using special-purpose foreign substances; sometimes they take advantage of some combination of rosin, sunscreen, and sweat, each of which is totally legal. the recent crackdown is basically only because it's a lever to improve batting. if offense got too good for some reason, i bet they would loosen up again.