Not much about pitching for the New York Yankees smacks of subtlety. When you are one of the most prolific strikeout pitchers in baseball and heir apparent to Mariano Rivera’s Yankee Closer throne, people tend to keep close tabs on your actions.

David Robertson fits the above criteria. In 2012, 32% of the batters he faces go down by strikeout, which is very good. His numbers in 2012 are very, very good as well. 27 Shutdowns, 1.5 WAR, 2.79 RA/9, 79 strikeouts against just 19 walks in a shade under 60 innings. Quite Good.

The thing is last year David Robertson was basically unhittable. He was a human version of 2012 Craig Kimbrel, posting a 13.5 K/9 rate and nearly 4 rWAR. Almost anything Robertson did in 2012 would pale in comparison to his superlative 2011 numbers. After an ill-fated turn in the closer’s seat an injury shelved Robertson for a month, the boatload of “what’s wrong with David Robertson?” blog posts and newspaper articles were all but inevitable.

Most smart outlets would not waste time with a “what’s wrong with David Robertson?” article if the answer was simply “regression to the mean.” Watching David Robertson pitch in 2012, something certainly appears different. The number one thing many are quick to point out: decreased usage of his hammer-of-doom curveball. Robertson’s main strikeout weapon is getting a little less play in 2012, especially in two strike counts.

(Via Robertson’s Brooks Baseball player card)

As a two-pitch pitcher, Robertson still uses his curvein two strike counts more than most pitchers because he doesn’t have much other option. But the downturn in curveball usage is clear and many think it is the culprit for his more pedestrian results in 2012.

The main scapegoat for Robertson’s (observed) diminished curveball usage is a sudden love affair with the cut fastball. Yankee lore holds that Mariano Rivera taught Robertson a cutter a few years ago and Robertson became enamored with the pitch to his eventual downfall. Yankees bloggers wrote letters, begging and pleading with the right-handed setup man to ditch his cutter for the more effective curveball he used to such great effect in the past.

This is where things get complicated on two fronts. First and foremost: David Robertson denies consciously using his curveball less. The 27-year old reliever denies it when reporters ask him about it and when I asked him on Friday afternoon he all but denied again. “I feel like I’m throwing about as much as I did last year. I mix it in when I need to and, whenever I need a big out, I use it.”

His catcher, Russell Martin, scoffed at the suggestion he calls for the curveball less, firmly stating the curve is “a plus pitch” for Robertson and that they, as a tandem “certainly have confidence in it.” Martin attributed the dearth of curves to “just the way it worked out” on a situational basis.

Watching his recent outings in Toronto, Robertson used his breaking ball liberally, never shaking off Martin’s two finger call for the curve. As Robertson told me, his main focus is always the same: making effective pitches. Strikeouts are necessary for any pitcher prone to walks but Robertson’s stated belief is such that making better pitches in better spots is the means to his end.

You may notice the above chart from Brooks Baseball lists only one fastball: the cutter. Prior to this weekend, it read only “fastball.” In “researching” this post, I stared long and hard at Robertson’s page on Brooks. Did I see a cutter? Did I see more than one fastball? Since the good men at Brooks manually assign pitch IDs, I reached out to pitch fx guru and one of the minds behind Brooks Baseball itself, Harry Pavlidis. I asked Harry if, in his esteem, Robertson threw more than one fastball. Had he increased his use of the cutter over the last year? Harry’s answer was brief and to the point: all he throws is a cutter. His fastball is a cutter and Harry adjusted his pitch chart to reflect this belief.

Pavlidis has stared at hundreds of thousands of pitches and has made this type of work his career. If Harry says it’s a cutter, it’s a cutter. Right? It certainly looks like a cutter to the naked eye and it appears to behave like a cutter when lasers measure its spin…so it’s a cutter.

Ducks, walking and talking and so on. It looks like a cutter and behaves like a cutter but, according to horse’s mouth and visual evidence, it begins its life as a four seam fastball. Odd. Very odd.

Except, of course, that David Robertson looked me right in the eye and said: no, I don’t throw a cut fastball. I only throw the same old four seam fastball I’ve ever thrown. No cutter. Just a boring old four seamer with some natural fade (paraphrased, obvs.)

So which is it? Look at the sidebar image on the right. This is a photo of David Robertson in the middle of his windup, halfway to firing another pitch in pursuit of another strikeout. This image was not chosen randomly. It features a lovely shot of David Robertson’s fingers as they grip the baseball. The image is clear but it serves to only muddy the waters further.

This photo shows David Robertson holding the baseball with a pretty standard four seam fastball grip. Across the seams at the widest part of the horseshoe. Just like your dad/mom/grandpa/nana/pushy neighbor with stars in his eyes taught you. The photo at the end of this link shows his curve grip, the blown up image below highlights his fastball grip. Looks like a pretty standard four-seamer grip, no? Not a baby slider or a “grip cutter” designed to impart increased side spin.

For whatever reason (physiology or will), David Robertson throws his normal four seamer with so much natural movement that it looks and behaves like a cutter. A cutter that, at times, lets him down. Location is never going to be Robertson’s suit though his swing-and-miss stuff, powered by the longest stride length in baseball, gives him an edge.

His curveball is a tremendous weapon but without good fastball command, it matters very little. All Yankees fans care about is David Robertson registering outs – no matter what pitches he uses. Whether or not his fastball is a True Cutter or not matters very little when he takes the hill in high leverage playoff situation. Just keep the runs off the board and the ball in the ballpark and everyone goes home happy.