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Guillermo Moscoso's New Pitch

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Update (1:30 PM): Kevin Kouzmanoff has been traded to the Colorado Rockies for a player to be named later.

Quick, see if you can name these two A's pitchers:

Pitcher A: 5.32 FIP, 3.47 ERA, 4.53 K/9, 3.47 BB/9, 1.36 HR/9
Pitcher B: 2.97 FIP, 2.90 ERA, 6.39 K/9, 2.32 BB/9, 0.29 HR/9

Pitcher A has a decent ERA, but it's just a mask on top of an atrocious FIP. He has a horrible K rate, and a huge HR rate. Pitcher B, on the other hand, has a tiny HR rate, strikes out a fair amount, and has an excellent ERA and FIP.

They're both Guillermo Moscoso.

A month ago, Moscoso re-added his cutter to his repertoire. Since then? He's been, surprisingly, one of the best pitchers in the Oakland rotation.


Click to enlarge.

The PITCHf/x movement chart on the left is all of his starts this year before July 30th, and the chart on the right consists of the five starts after the 30th. See the new purple set of dots that's below and to the right of the red fastball dots? That's the cutter. His new cutter comes in around 84 mph, a bit faster than his 80 mph changeup, but it's far slower than his 92 mph fastball. Most cutters are only a few mph slower than the fastball, and they tend to have more lateral cutting movement than vertical sink, both of which makes Moscoso's rather unique. If I had to guess without looking at what he calls it, I would have called it a slow splitter, or a splittery slider. It seems to move and act like one.

Whatever it is, it seems to be working. Before the new pitch, Moscoso's peripheral stats set off nearly every single sabermetric red flag in existence (insanely low BABIP, very low HR rate considering his massive flyball tendencies, enormous FIP/ERA differential). After? His BABIP actually regressed a bit to vaguely normal levels (.250), his ERA fell in line with his FIP, but best of all, his ERA and FIP have decreased by huge amounts, because he's striking out almost two more batters per nine innings. His HR rate has decreased to microscopic levels, but I'm uncomfortable drawing any cutter-related HR/FB conclusions due to the tiny sample size.

I don't know if Moscoso is long for the rotation, since he's nearly in the double digits on the SP depth chart, but this new pitch certainly seems to be helping his chances. Brett Anderson and Dallas Braden won't be back from the disabled list this year (and possibly even longer), so Moscoso should probably expect to have until the end of September to prove his worth.

The A's open a three-game series against the Yankees tonight (Brandon McCarthy vs. Bartolo Colon) at 4:05 PM PDT.