Grips, regardless if it’s a slider or any other, depends on how your feeling on any given day, the surface conditions that your on, and some other particulars. Seeing how we’re not in the professional game with its multi-million dollar stadiums, trainers and the like, we have to make adjustments to our grip…in addition to other things, sometimes after every pitch.
So, to help you with the basics… something called ADJUSTMENTS… here’s what I suggest:
get a good baseball and mark it up with different finger, palm and thumb positions.
now try various grips and see just how effective you pitch is.
did it performan the way you wanted it to?
of course an over simplification is… try adjusting your grip.
the markings on the ball will at least give you a REFERENCE POINT of where you were last… and the witness of what happen or not.
The picture below should give you some indication of how to mark a ball for this excercise. By the way… pitching coaches call this method of starting and referencing you finger - palm - and thumb placements …
Dialing the Ball.
Hope this helps you.