Knuckleballers aren’t like other pitchers, or so the saying goes. Their pitches flutter like butterflies, they pitch at less than max effort, they don’t depend on velocity, and they can pitch into their fifties. All of these things seem true, and yet the more we know about knuckleballers the more they might actually be more like all the other pitchers out there. So when 38-year-old R.A. Dickey has lost some oomph on his seminal pitch, maybe it means something, just like it usually does for other pitchers.

First, the fluttering. That might be an optical illusion. R.A. Dickey doesn’t agree, but scientists and physicists that have studied the path of the knuckleball agree with Professor Alan Nathan that it behaves ‘generally’ like other pitches. The unpredictability might still be wonderful, but it’s physically impossible for the ball to break multiple inches in each direction. The ‘dancing’ might be our minds trying to figure it out.

Next the max effort thing. Dickey said he throws at about 75% of the effort he spent as a traditional pitcher. So that much may be true when it comes to rest and recovery.

But it takes effort to put velocity on the ball. And we’ve seen that Dickey’s ‘fast’ knuckleball is probably the best one in his arsenal. The pitcher himself told me in an interview last year that he’d been getting more swings and misses from the fast knuckler. Professor Nathan found that velocity and movement were negatively correlated for the knuckleball, and it seems that Dickey’s elite control for a knuckleballer might have been at least partially due to the velocity on his most important pitch.

Now Dickey’s three-year run of above-average control is in jeopardy. As you might have guessed, it’s not from a lack of movement. Professor Nathan plotted the movement this year and last year and found little change. But perhaps there is still something different about his knucklers this year. His velocity is down two miles per hour on average.

Dickey throws a few knuckleballs, and the error bars on his velocity readings are large. Let’s look at the distribution of his knuckleballs instead of a straight average. Using three-mile-per-hour buckets, I plotted all of his knuckleballs from four distinct periods below. The first is pre-breakout Dickey. The second is 2010-2011 Dickey, who was great but not elite. Then you have Cy Dickey and this year’s Dickey.

Those purple bars might have a little too much in common with the blue bars of Dickey’s darker days in baseball. They certainly don’t fit with his Cy Young year, and in some ways, they don’t even look like the 2010-2011 version. In 2010-2011, 34% of the knuckleballs Dickey threw went faster than 78 mph. In 2012? 47%. And this year he’s been throwing those fast knucklers 16% of the time.

Dickey’s still getting whiffs this year. His 9.9% whiff rate puts him in the top 30 among qualified pitchers. But after three years spent walking less than six percent of the batters he saw, his walk rate is in the double digits this year. Maybe he has a little lost velocity to blame, since the pitch should have the least movement and was his go-to pitch in hitter’s counts last year. And, considering his back and neck problems this year, and his abdominal and hip and plantar fasciitis issues last year, it may be fair to ask if his body is robbing him of this velocity.

Is that too conventional a question to ask of a knuckleballer?

Here’s the distribution of Dickey’s knuckler velocity in half-mile buckets just for good measure: