Daniel Herrera throws a pitch not often seen in the professional ranks these days: The screwball. Before Thursday’s double-header, I asked him and his catchers about it. I included my questions below where necessary:

Herrera: I learned to throw it in college. When I was a freshman I had a pretty bad changeup, and I dropped my arm slot to get more movement on my fastball. I started fooling around with grips and different ways to throw it, so pretty much I was just kind of pronating my changeup more and more until the spin was on the side. And eventually the spin started getting on top, moving like a curveball.

It was just messing around with a lot of things, a lot of trial error with what would hurt my arm and what wouldn’t. It definitely puts a lot of torque on my arm, but thankfully my elbow has held out.

I started throwing it in games my sophomore year in college. Since then it’s been my bread and butter pitch. I don’t think I’d have much of a chance if I didn’t have it.

I use it more heavily to righties. For lefties, it kind of comes back to them. I still throw it to lefties quite a bit, but I favor it to right-handed hitters.

Me: I read that you throw it with the index finger off the ball.

Herrera: (Grabs a ball and demonstrates the grip. It looks like a circle change, but with the index finger bent behind the knuckle of the thumb and a big space between the middle and ring fingers. The middle finger runs along one seam, with the ring and pinky fingers gripping the opposite side of the ball.) Yeah, I use the horseshoe to really pull down the ball. These two fingers (the ring and pinky) are basically for comfort, and the thumb just holds it in the hand. But the index finger is definitely off the ball.

When I release it, it’ll be right around here (turns his hand over so the circle made by his thumb and pinky faces straight down). Same arm slot, just a different release.

I know that hitters can see it more than my other pitches because it goes up out of the hand. It’s the only pitch that goes up before it comes down. Everything else is straight and then starts moving, and the breaking ball kind of goes around like a Frisbee. The screwball, when I do throw it, goes up.

Me: Do you know of anyone else that throws the screwball?

Herrera: I’ve talked to an old pitching coach I had with the Reds, Tom Browning. He used to throw it back when he pitched, but I don’t know anyone else who throws it now.

Mike Nickeas: His first day was in Washington. He came in, and I hadn’t had a chance to talk to him about his stuff. I heard he had a screwball. It was pretty neat. I was pleasantly surprised — he’s really effective. He throws the big one that acts like a curveball from a righty, and he has one that he throws lower that kind of dies before it gets to the plate.

It moves a lot, and the speed change is really dramatic. A lot of guys get out on the front side, and it’s a great pitch for groundballs -– easy outs.

I’ve never seen one before. It’s something that was new to me, and I was kind of nervous in anticipation, waiting to see what it was going to do. And it was pretty good, I was impressed.

Me: Is it a tough pitch to catch?

Nickeas: The knuckleball’s tougher just because it’s unpredictable. Once I get a feel for Herrera, I know which was it’s going to go. The knuckleball’s still the worst thing you have to deal with as a catcher.

Josh Thole: It’s a good pitch. It’s different. It looks like a changeup more than anything, but it’s different when you know what’s coming. I don’t know what it would look like when I’m hitting.

It’s the first time I’ve ever seen one. I’ve seen it on TV and all that, but it’s different. It’s an effective pitch for him. It moves pretty much like a right-handed curveball, I guess is the best way to put it.

Ronny Paulino: I think the knuckleball is more difficult. It’s weird rotation, no question. It’s weird; I faced him but it looked totally different. It looks different when you face him and when you catch it. It’s hard to explain.