In Sunday night's game against the Cincinnati Reds, Detroit Tigers pitcher threw a high four-seam fastball. That in and of itself wasn't noteworthy, but what is noteworthy is what Valverde did immediately beforehand.
MLB rules prohibit the "doctoring" of a baseball before pitching. According to the rules, a pitcher may not "deliver a ball altered in a manner prescribed by Rule 8.02(a)(2) through (5) or what is called the "shine" ball, "spit" ball, "mud" ball or "emery" ball. The pitcher is allowed to rub the ball between his bare hands."