Stuff: heaters and hammers, splitters and cutters, Uncle Charlies and Lord Charleses. Stuff describes the weaponry one side carries into the game's most elemental battle: pitcher versus batter. Hurlers either have stuff or they don't—and when they do, it's the major league hitter's job to figure out how to handle it.
So who handles what, and how well? Every team employs an army of advance scouts to discern just that, to learn which hitters mash the fastball but buckle at the curve, who waits on the curve but becomes hopelessly coiled in the face of the change. That information is invaluable, but like all intelligence, it can be influenced by opinion and the vagaries of the human eye. That observational data is complemented by a more scientific method of gauging hitter performance. The baseball analytics website FanGraphs features a stat called Pitch Type Linear Weights, which examines how productive hitters are against the most common pitches in the major league arsenal. In simple terms it's a measure of how successful a player has been against a particular pitch. That performance is expressed as the number of runs a hitter creates above (or below) the average level for a major leaguer. For example, Yankees second baseman Robinson Cano was rated as the most productive hitter in the majors against the slider in 2010: Per 100 sliders seen he created 4.47 runs more than the average big league hitter.
PTLW isn't a perfect stat. It doesn't take into account defense, among other factors, and it can be skewed by sample size. But it provides a general measuring stick of a hitter's performance, the way ERA does for a pitcher. The following pages name the five most productive hitters in each league (listed with 2011 team) based on their 2010 PTLW against the fastball, curveball, slider, splitter, cutter and changeup (ranked by runs created per 100 pitches). Statistically, these guys had the right stuff.
"I didn't know I was a good slider hitter. I don't look for any special pitch, just for something in the middle of the plate. That's the only way to drive the ball."