=== He Can Call It A Forrest Fire, A Snow Flake or a Bahama Breeze ===

.... but Felix' new pitch will still cut in on left hand hitters.  

Whatever way he takes hold of it in the mitt, whatever the name, whatever the catcher's signal, the FLIGHT OF THE BALL is the same.  It's a 92 MPH pitch that spins toward LHB's and slides in on them.

From a hitter's standpoint it is a cut fastball, end of story.

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=== Not QUITE Unique ===

There are apparently two guys who can throw this pitch, or who could, anyway.  The other guy, Mariano Rivera, also throws his murderous cut fastball with a 4-seam grip, as shown in the picture above.  As far as the semantics are concerned, you could say that Rivera doesn't throw a cutter - just a four-seam fastball with ridiculous movement. 

Rivera could call this pitch a "four seam fastball" if he wanted, or he could call it a "cut fastball," since he spins it like a slider.  Same with Felix.  The semantic problem with that is, "four seam fastball" is currently used for high-velocity fastballs that tail armside and rise.  Felix' cut fastball does not do that.  It'd be like saying Ichiro's three-hopper through the SS hole is a bunt.  You could call it that if you wanted - it's a free country - but "bunt" is already used for something else.  Why confuse the audience.

How a pitcher takes ahold of the ball, that is what is captured by the phrases "four seam," "two seam," "knuckle curve," "splitfinger" and what have you.  A cut fastball could theoretically be thrown with 4 seams, 2 seams, or one seam.  The grip used does not capture the essence of the pitch.  The semantics "four seam fastball, "cut fastball" or "Forrest Fire" leave us in the dark as to what's happening.  What's happening is that Felix is, impossibly, throwing a 93 MPH pitch that breaks gloveside.

What defines a pitch is its flight, the spin and release - the angle at which he chooses to spin the ball, the pressure on the fingers, etc.  The spin on Felix' cutter, left-to-right from the catcher's POV, is leaving hitters for dead.  He's inhuman, I tell ya, inhuman.  :- )

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=== By The Numbers Dept. ===

Last night we didn't even mention the most important number:  that Felix' 29 four-seamers er Bahama Breezes er Felixballs er cut fastballs er call it anything you want but don't call it less than once a batter, on those 29 sliding fastballs, his "Linear Weights" was -1.36 runs saved.  Every time I've checked the results on his cut fastballs -- those fastballs that have a positive horizontal break, a gloveside break -- the "Linear Weights" show him as saving more runs than actually occur in a game.

In English:  Felix' cutter has been pretty much the best pitch in baseball.  He seems to have noticed this fact, and is throwing it more and more, apex'ing (so far) at 29 pitches last night.

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Thanks for that comment below Nathan.  :- )  A tip o' the kelly for SSI is fine, but it's AL hitters who are going to feel the pain.  This 5th pitch may turn out to have a geometric effect on their problems.

Love, love, love the fact that he threw it 30-odd times Friday.

BABVA,

Dr D