This is the kind of stuff we deal with seemingly every weekend in youth sports. The administrators tinker with the rules and the coaches and players try to figure out "work-arounds" to the application of the rules. I went to the best source I know of in the area of pitching and safety issues -- Dr. Mike Marshall. He was gracious, as always, with an interesting reply.
Dr. Mike Marshall's Pitching Coach Services
I'm umpiring an 11U tournament where the pitching restriction is no
curve-balls allowed. Prior to the game, the coach of one team said they
exchanged e-mails discussing how their pitchers throw a
"knuckle-slider". I had never heard of such a beast before, but per
Wikipedia, it exists as such:
"The knuckle slider is an uncommon pitch in most of baseball. It is a
pitch that breaks to one side at about the same speed as a normal
slider. Its intended use is to make the batter over-anticipate and swing
early. Also, because of the pitches breaking nature, it is very hard for
the batter to make good contact. Often, these pitches will foul off or
pop up. Hot to throw: Start off with a knuckle curve, then turn your
wrist 90 degrees to the right (for a right-handed pitcher). There is no
need to supernate (they mean 'supinate')or pronate your arm because is
already cocked. Throw it with the same arm speed as your fastball."
Of course, I've heard of its close cousin, the knuckle-curve:
Again, per Wikipedia:
"In Major League history, the term knuckle curve has been used to
describe three entirely different pitches. The first, more common pitch
called the knuckle curve is really a standard curveball, thrown with one
or more of the index or mean fingers bent. According to practitioners,
this gives them a better grip on the ball and allows for tighter spin
and greater movement. In all other respects, this knuckle curve is
identical to the standard curveball."
My dilemma as an umpire is enforcement. In a one man crew, I'm somewhat
limited, so I apply the "duck-rule" i.e. if it looks like a curveball,
and rotates like a curveball, and moves like a curveball -- it's a
curveball. They can call it a lampshade for all I care.
The team in question's first pitcher throws a couple of hanging
spinners, both of which get crushed, so I don't penalize. The second
kid, a lefty, throws a nice little bender. ILLEGAL. The coach moans a
little, cites their "gentleman's agreement" that the knuckle-slider is
OK and safe to pitch. I tell him I neither know nor care about his
pre-game e-mails, I'm going by what I see and their tournament rules. I
explained to their other coach (they had a pitching/hitting coach, it
seems) that if the rules are "curveball bad" in my opinion "slider
worse" so why they think that calling it a knuckle-slider helps matters
is beyond me. They call it a "safety pitch" rule for a reason.
BTW, the kid could not throw a FB for a strike, and believe me when I
say at that level (and most others), I'm considered to have a
pitcher-friendly strike zone. Sadly, it seems like the "hitting coach"
understood my argument (and the suggestion that maybe he should learn to
throw the FB for more strikes, mix in a straight change here and there)
more than the "pitching coach" and dad.
1. Am I missing anything on the alleged safety of knuckle-curves or
Their point is since it doesn't require the pitcher to twist his wrist,
From an enforcement standpoint, there's no way youth umpires are going
to be able to see that and call balls-strikes (never mind balks, and
they do lead/steal) at the same time.
Thanks for letting me vent a little. Just when I thought I'd seen and
heard it all....
Phone: (813) 335-8678
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The difference between sliders and curves is that sliders spiral
with a horizontal spin axis that points toward home plate and that
curves rotate with a horizontal spin axis that points sideways.
The knuckle curve release means that baseball pitchers use their
Thumb and Little finger to hold the baseball against the front surface
of the finger nails of the Index and Middle fingers and release the
baseball by extending their Index and Middle fingers.
With regard to your obligation to enforce the no curve ball rule: I
agree with your "if it looks like a curve ball, then it is illegal"
However, I disagree with why the organizers of this 11U tournament
do not allow the baseball pitchers to throw curve balls.
You said: Their point is since it doesn't require the pitcher to
twist his wrist, it's safe.
That means that, to throw curves, when baseball pitchers do twist
their wrist, they will injure themselves.
By twist their wrist, if they mean that baseball pitchers 'supinate'
(turn their forearm such that the thumb of the pitching hand points
upward and release their curve over the top of the Index finger, then
throwing these curve balls is injurious.
So, the question is: Are the organizers of this 11U tournament
against throwing all methods for throwing curves or just the
'supination' curve technique?
Because, as you said, it is impossible to determine whether baseball
pitchers 'supinated' the release of their curve or extended the Index
and Middle finger to release their curve, I agree with your ruling.
Nevertheless, the knuckle-curve release is not injurious. However,
as you also noted, it is very difficult to master.
I designed another way for baseball pitchers to throw injury-free
curves that I have watched eleven year old baseball pitchers learn in
I call this pitch, my Maxline Pronation Curve.
When my baseball pitchers throw pitches toward the pitching arm side
of home plate, I call those pitches my Maxline Pitchers.
Therefore, the difference between how I teach my curve versus the
'supination' and 'knuckle' curves is that my baseball pitchers 'pronate'
the release of my curve.
Whether 11 years old or 21 years old, the 'twist' of the wrist that
injures baseball pitchers is that they 'supinate' their pitching forearm
through release. This action causes baseball pitchers of all ages to
bang the bones in the back of their pitching elbow together.
Needless to say, banging the bones in the back of the pitching elbow
is not a good thing to do. When baseball pitchers 'supinate' the release
of their curves, they seriously and irreparably damage those bones.
However, when baseball pitchers use the nails of their Index and
Middle fingers to push the baseball forward or 'pronate' the release of
their curves, they do not bang the bones on the back of their pitching
Therefore, I will teach baseball pitchers of all ages how to throw
my Maxline Pronation Curve. It is not injurious and, to become the best
baseball pitchers that they can be, all baseball pitchers must master
Dr. Mike Marshall