07 April 2011

Josh Rupe: No. 1

One finger down has traditionally been synonymous with a fastball.  Josh Rupe knows this well.  He knows this so well that he probably is confused when he sees anything else.  At least, this was probably true last night.  Josh Rupe threw 51 pitches over parts of four innings.  He started off with a slider, then mixed in 16 four seam fastballs, a slider, then 17 four seam fastballs, and at this point he decided to mix things up with four seamers and sliders.  It was a remarkable night because I often saw this type of pitching when I was in travel leagues as a teenager.  This approach is fairly uncommon these days.

I think part of Rupe's ability to do this is that his four seamer gets considerable run into right handed batters.  Thrown with good command and control, it is a pitch that will force a good deal of poor contact.  Based on Pitch f/x data, he averages about 8 inches of horizontal run on the pitch.  That aspect of it was the most of any pitcher who threw last night.  The four seamer has enough movement that he can basically throw it over and over again.  However, if his command is slightly off, batters can tee up something that does not run as much or settles into the middle of the plate . . . as we saw last night.  His slider is merely a show me pitch that he uses merely to keep batters off guard with slight movement in the other direction and a change of speed.  If used sparingly, he can throw it for an uncontested strike or get a swing and miss due to sheer surprise.

Here are the numbers...

Four Seam Fastball
Count: 45
Strikes: 28
Swing and Misses: 4
Velocity: 91.6 +/- 0.9 mph
Horizontal Run: -8.2 +/- 1.4 inches
Vertical Drop: 6.4 +/- 1.3 inches

Count: 6
Strikes: 5
Swing and Misses: 1
Velocity: 84.1 +/- 1.75 mph
Horizontal Run: 4.4 +/- 0.9 inches
Vertical Drop: 1.8 +/-  1.3 inches

To understand the horizontal and vertical movement, it is good to read the Physics of Baseball by Adair.  A normal projectile should have a no movement (0 inches, 0 inches).  There is no such thing as a rising fastball, but there is such a thing as a pitch that does not drop as fast as it should (or faster than it should).  This is due to the seams on the baseball and how its flight can change due to them.

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