"Felix' fastball, which is usually really straight, was cutting today." - Adrian Gonzalez, in response to a question as to why Felix was unhittable, June 28, 2012
Q. Why the semantic debate over Felix' cut fastball?
A. Naming pitches, naming pitches, naming pitches... people have been arguing about the right names for star pitchers' weapons since, oh, about 1880. It used to be a lot more popular than it is now.
The fact that we're arguing about whether Felix' inward-breaking fastball is a "cut" fastball is actually a refreshing blast from the past. People used to have fun arguing about this stuff, back when F/X couldn't resolve it. Nowadays it's a lot harder to argue about it.
SSI has demonstrated, using literally 5,000 to 10,000 words, that Felix is throwing a new pitch and that this pitch is a cut fastball. Sources peripheral to the M's respond with like five terse words -- "Felix doesn't throw a cutter" -- and absolutely zero substance.
Somebody said "well, he uses four seams." We published a picture of Mariano Rivera's fastball. You can guess what the reply to that was. Zero.
Q. Supposing that the pitcher himself doesn't call it a cutter?
A. Pitchers themselves have been part of the semantic confusion since, oh, about 1880. You'll find guys from the deadball era vociferously denying that they threw curves; what they actually threw, you understand, were "drop pitches." They didn't throw sliders or nickel curves; they threw "inshoots" and "sailers."
There's a real imperative for pitchers to cast their arsenals in the most glorious possible light. ;- ) In the 1980's you found pitchers objecting to the term "forkball"; they threw Split-Fingered Fastballs.
Q. What's inglorious about cut fastballs?
A. For 95% of pitchers, cut fastballs are defensive pitches. You throw them to survive.
A right hand pitcher throws a "cutter" to a left hand masher - say David Ortiz - at -5 MPH, breaking in on his hands. If Ortiz swings, they hope that Ortiz will top it ... "I know you're going to hit this. Please hit it at somebody!" type thing. If they're lucky, they "saw him off" a few times, break his bat by getting inside the label, a description that maybe adds a bit of pizazz to an otherwise defensive strategy.
And if they're lucky, Ortiz becomes aware of this cutter, over time, and backs up an inch. He stops leaning out over the plate. And then they can throw The Coin Of The Realm, an outside-corner, armside-sailing Manly Fastball that Ortiz will swing under and strike out on. Got him with my Heater!
Mariano Rivera was, uniquely, proud of his cutter - and he threw it 90% of the time. Special Case Territory. Who are others... Roy Halladay isn't exactly ashamed of his, but have you ever heard him bragging on it? Cliff Lee became The Great Cliff Lee when he learned a cutter, but you'll never hear him emphasizing it.
Here is Felix Hernandez, throwing a Rivera cutter, and his preferred term for it seems to be "Four Seam Fastball With Ridiculous Movement." Felix evidently enjoys this phrase "ridiculous movement." Everybody associated with the Mariners uses this "ridiculous" adjective. Exclusively.