Fastball having slider-ish spin

my 4sfb has slider spin but not quite a true slider spin if that makes sense

its inbetween slider and straight FB spin

i throw from low 3/4

what can cause this?

you’re having the little kid syndrom, as i like to call it. watch most young kids pitching, their fastballs when they pitch or even when they throw on the field spins like a bullet. how old are you? basically you’re throwing a natural cut fastball, which is good depending your age, but you do want to have a regular fastball as well, if i had to take a guess id say you throw with your middle finger being the last finger touching the ball. if that’s the case, work on releasing the ball with your index finger being the las finger to touch the ball. if that’s not the case, you’re throwing with your arm being supinated, meaning your pinky finger is what the catcher sees when you throw. try and work it so the catcher sees your thumb. it’s called pronating and is why pitchers get telling action on their fastballs. if you can control it, your actual fastball could become a weapon of mass destruction, Roy Halladay-ish.

hope that helped in any way.

im 15 playing varsity ball and im not 100% sure but i think i release with the ball last ouching the middle finger cuz on the inside of my right hand [rhp]… inside being the side of the middle finger closest to the thump is always becoming rough after throwing from the ball

i tried putting pressure on my index finger today with the fastball and it sunk, but without the downward movement which i guess is a running fb?

so i thought id keep both the running fb and the cutting fb

Check your grip and see where your thumb is. Do you have it part way up the side of the ball? This can cause a slider like spin and has the potential to put stress on the tendon that attaches to the medial epicondyle on the inside of the elbow. Make sure your thumb is directly below your 2 fingers that are on top of the ball.

thump is under the ball and in between my 2 fingers on top

well said

In my experience this is an indicator that you are "casting’, some call it leading with your pinky…what it is is not getting your hand behind the ball, it stresses your shoulder and makes it difficult to be consistant. The easisest trick to indicate this is to put a pirce of tape around the axis of the ball, if it wobbles or doesn’t give a nice smooth line (No matter the arm slot) then your hand is not behind the ball and an adjustment should be made. Yes you can have success throwing that way but it will only get you so far and velo and shoulder security are the “victims”.

what adjustments would be necessary if the tape is wobbly or not in a straight line?

Back up, commence throwing from a fundementally sound position and work up to your normal delivery. The idea is to naturally keep your hand behind the ball, at first it takes a little concentration but when you get it right…it feels sooo right and becomes second nature…you’ll notice more velo, more control and very likey very solid breaking ball.
Let us know

Fun pitch to use occasionally, but as JD suggest can lead to some problems if used a primary fb. When I see that “little circle” from my kid. the queue I give him it stay behind the ball a little longer (dont let finger slide to the side) and pronate at release …

dumb question… but what does it mean to stay behind the ball?

That’s a good question, I know what it is but I couldn’t give you a good answer. I’d have a tough time explaining it.

Keeping your hand behind the ball…is self descriptive (No question is dumb…by the way…any who treat it that way are impatient and poor in their teaching method) as you throw a baseball, your hand releases a ball in a certain way, the way you described it in the op is that your hand actually gets “outside” of the ball…in other words during release the ball is between the palm of your hand and your body, this is an inefficient way of delivering the ball. What you want, is to get the most control and potential velocity…this is done by keeping the fingers and palm of your hand brtween your body and the ball as you deliver. It would seem a simple thing, but in an effort to get velocity or movement too many pitchers lose control of their arm and where the ball leaves their hand…leading to “casting”, once being made aware of it, it is a realatively simple thing to correct…in the way I mentioned…but a bunch of shoulder injury has happened because guys haven’t got that figured and continued to cast for extended periods of time. Now for certain breaking pitches you will as the arm and shoulder drives forward cause your hand to supinate slightly (In the case of a slider) but this should be a wrist caused effort not the effort of turning your arm over…even with the curve, you are throwing a fastball until it’s even with your shoulder and then getting your fingers on top of the ball (Which again should be more of a wrist function) you pull it down in front of you. I hope this makes better sense to you.