This article appears in the June 14 issue of ESPN The Magazine.
Ben Sheets' curveball is widely regarded as one of the best in baseball, a pitch that fools hitters more often than not. So the A's were initially perplexed back on May 2 when the Blue Jays swung repeatedly and aggressively at Sheets' out-pitch, attacking the ball like a pinata. Toronto mashed three extra-base hits against the curve that day, racking up nine runs in 3 1/3 innings against Sheets. And while any pitcher can have a bad outing, it was the Jays' approach at the plate that made the A's coaches suspicious. It was almost as if the hitters knew what was coming.
Another piece of information contributed to the Athletics' suspicions. Toronto manager Cito Gaston is known as one of baseball's best at recognizing when a pitcher is tipping his pitches. Players say that Gaston can detect the most subtle tells, like a great poker player reading a bluff from a minor twitch. So it wasn't a huge leap to think Gaston had noticed that Sheets was doing something every time he threw his curveball.