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On The King Felix Royal Curve

Stephen Dunn - Getty Images

In a very short amount of time, Felix Hernandez will take the mound to make his final start of the 2012 season. Because it's at home, it's also the final King's Court of the 2012 season, and Felix will be pitching against the Angels. Felix has a chance of being the guy who knocks the Angels out of playoff contention. The Angels will be eliminated with either a loss or an Athletics win over the Rangers, and the A's game starts five minutes before the Angels game starts, but that other game will be started by Martin Perez and Jarrod Parker and we've seen Felix cruise. I wouldn't say no to a two-hour complete-game Felix shutout. I guess I wouldn't say no to a four-hour complete-game Felix shutout? Basically, Felix could do the ultimate spoiling, is the point.

Because Felix is pitching tonight, and because I love reading about and analyzing Felix, I decided to get myself lost in the numbers. When I'm lost in a statistical forest, I have to find a statistical path out of it, and that's how blog posts are born. Before we get to the point -- Felix's curveball is known as the Royal Curve. It's been called the Royal Curve for years and years, and while we all loved it when Felix first came up, my sense is it's fallen behind a bit in popularity. The pitch people are most in love with is Felix's unhittable changeup. He can also throw an incredible slider and a couple difficult fastballs. Everybody knows that Felix throws a curveball, but maybe they don't appreciate the curveball's quality.

So, here's a .gif. It's Juan Rivera vs. Felix Hernandez on May 7, 2010. For Felix, that was just an absolute disaster of a start, but we're not here to talk about that start. We're here to talk about the .gif, and what it means.


That's Juan Rivera going yard against a Felix Hernandez curveball. Felix hung it and Rivera put on a good swing. That is also the last time Felix's curve was hit for a homer. May 7, 2010 was nearly three full seasons ago. Felix has thrown a lot of curveballs ever since; not a one of them has been batted over the outfield wall.

According to Brooks Baseball, Felix threw 521 curves in 2011, allowing zero homers, zero triples, and four doubles. From the same source, he's thrown 376 curves in 2012, allowing zero homers, zero triples, and zero doubles. We're limited by the PITCHf/x accuracy, and on rare occasion does PITCHf/x take a pitch or a plate appearance off, but based on the best we can do Felix has thrown nearly 900 curves the last two seasons combined, and batters have swung at 340 of them. Those swings have produced four extra-base hits, all of them doubles.

We can take it even further, because it's fun to do that. Of those swings, 118, or 35 percent, have whiffed. For many pitchers, the curveball isn't a swing-and-miss pitch as much as it's a freeze-the-hitter pitch, but Felix has generated the same whiff rate with his curveball as he's done with his changeup. And on top of that, when hitters have put Felix's curveball in play, two-thirds of the time the ball has remained on the ground. It's both a swing-and-miss pitch and a groundball pitch, and Felix has pretty good command of it, too. He can put it in the zone and so it can't be mentally eliminated as a strike.

This season Felix has thrown his curveball least of all, slightly less often than he's thrown his slider. This is not a plea for Felix to throw more of his curve, because the usage pattern is presumably responsible for a lot of its success. This is simply an acknowledgment that the Royal Curve is very much regal, and to this day it lives up to the hype that it used to receive. Felix is about to make his 33rd and final start of this season. He made 33 starts in the last season, and 34 starts in the season before that. In that 2010 season, Felix allowed a home run on his curveball in his seventh start, and a curve hasn't been driven out since. That's a lot of unhittable curves, and precious few hittable curves.