4 seam, 2 seam command issues

Hi everyone, been reading you for a while, glad to join you at last!

I got an issue with my 4 seamer command. It always goes down and away from the zone. In the same time when I throw a 2 seamer it goes just fine, fully straight. When I add some pronation, it goes down and inside (to rightie) just like it should. But I just cannot make my 4seamer go straight. What may be the issue? Thanks!

If your 4-seam moves down and away, then you must be putting some spin on the ball. Make sure you’re not supinating the pitch. Check your grip to make sure thumb and middle finger cut the ball in half (i.e. no off-center grip).