From a rules perspective, the buzz around baseball has to do with Marlins pitcher Carter Capps. Check out this delivery:
Well, it certainly is odd. Of course, odd does not equal illegal.
What does the rules have to say about this? Surprisingly little. The only real requirement in the rule is that the pitcher has to start on the rubber when delivering a pitch. There is no language that the pitcher has to be on the rubber at delivery. I would wager that most pitchers have already pushed off the rubber when the ball is released.
This now gets us into softball territory. A “crow hop” is an maneuver in softball where the pitcher replants their pivot foot effectively shortening the distance of the pitch. They are allowed to push off but not hop and replant.
The telltale sign of a push off is the dragging of the feet. It looks like MLB wants to use a similar guideline per this article.
“They just said they wanted me to make sure I dragged my foot and not get too elevated in the air, and make sure it’s more on a lateral plane,” Capps said. “As long as I do that, they have no problem with it. But it was very strange.”
Very strange indeed. It looks like as long as his hop is not over the top, MLB is going to allow this delivery.
In a nutshell they are ruling this: he has an extreme push off the rubber but it is a push off. He starts his delivery from the rubber.
Now, if they ruled this a hop to a secondary point and then a delivery with a push off, you would have an illegal pitch for delivering off the rubber.
I can see no reason why it would not be legal in other codes for similar reasons. It will be interesting to see if anyone codifies what can and cannot be done through case plays or book additions in the coming years.
Pitching positions are covered on pages 18 and 19 of RuleGraphics.