On Wednesday, Moshe pointed us to an article on Rational Pastime called “Mariano Watch: April” which detailed in glorious fashion the interesting phenomenon surrounding Mariano’s cutter.  The piece first began by showing that Mariano’s fastball velocity is down when compared to this time last year.  As you can see in the chart below (courtesy of Rational Pastime), he’s ranging between 0.2 and 0.6 mph slower on the cutter so far.

Fangraphs confirms that his velocity has been on a downward track since 2007, but this isn’t really news to Yankees fans.  J-Doug wonders, as have many analysts, why Rivera’s effectiveness hasn’t decreased along with his velocity.  He plots the average break on Rivera’s cutter, using all kinds of fancy math, and notes that the cutter is breaking a full inch more in 2010 than it is in 2009.  To wit:

So why I am bringing this up again?  Well, a few months ago Moshe tweeted that a source, which was me, passed along some insider information about Rivera and his approach to his cutter.  Rivera wasn’t concerned about the drop in velocity, and the reason was the he had noticed that he was able to generate more break on the cutter when it was thrown slower.  Now, from a physics perspective, I’m not exactly sure why it works like this.  Is it simply a matter of it taking slightly longer to get to the plate, and having a longer time to “spin”? Or does the velocity affect the break of the cutter in a different, more fundamental way? Does throwing it 3-4 mph faster make it straighter?  Can anyone explain Mariano Rivera and his ability to defy aging?

When I originally heard this information about his cutter, I thought it was cool and interesting but maybe just a tad bit apocryphal.  It sounded like the kind of story you hear a hundred times over in Spring Training: Player X lost 20 pounds, Player Y learned a changeup (ahem, Hughes), Player Z got LASIK.  Far be it from me to doubt the great Mariano Rivera, but I wasn’t absolutely certain that the Pitch F(x) data would back up his claims.  But Rivera was right.

There is, quite obviously, an uneasy tension between the more stats-oriented fanbase and the “scouting” fanbase, if I could use two very general and inaccurate terms.  I enjoy participating in the mocking of the stories like the ones I listed above.  I’m skeptical of any story written about how a player got a new workout routine and seems poised for a breakout year, unless it’s based on firm statistical analysis.  There’s a good reason for this: most of the stories turn out to be nothing more than filler that helps pass away the interminable days of PFP and intersquad matchups in March.  But beyond that, and I’m certain that I’m not the first to suggest this, maybe there is room for a little “mystery” when it comes to approaching this game.  In this case, the narrative of Mariano’s cutter preceded my ability to verify or validate it, but it was true nevertheless.  I like this.  And I like that people smarter than me are able to prove Rivera, who was just going on his sight and his feel, correct.  There’s a lot of tension, even dislike, between the camps of stats vs. scouting, new vs. old, proof vs. feel, etc.  A lot of times there doesn’t seem to be too much respect or open-mindedness in the conversation.  In this case, I appreciate that the two don’t need to be mutually exclusive.  Mystery and hard science can live next to each other, one validating the other.  And who better to embody it, to stand in the middle, than the great Mariano Rivera?