The following is a basic overview of what potential mechanical issues your QB may be having as it relates to bad balls he may be throwing (The issue(s) and potential mechanical fixes will be related to a right-handed QB in this blog). By no means is this the end-all be-all reason for the throwing issues but rather a good starting point for trying to figure out what is going on with your QB.
Ball is not spiraling:
QB is probably either gripping the ball too tightly, “palming” the ball (need to keep a little air between palm and ball), or not following through the throw by working throwing thumb downward to “opposite pants pocket”.
Throws to the left sometimes go “wide left”:
This is probably due to the QB “opening” up his front foot/leg too much to the left. “Unlocking” the hips too much will carry the ball a little too far left. (This is the same for a left-handed QB throwing to the right)
Ball tends to “sail” a little too high from intended target:
More times than not the issue here is that the QB has too much bend in his back leg when he hits his final step in drop or hitches up to throw which force the shoulders to angle upward. In turn, this will usually force the ball to be thrown a little higher than intended.
Another side effect of this happening is that the front leg of the QB tends to get “locked up at the knee” on throw which forces the lower body to stop its forward motion on transition from back to front leg. In severe cases this locking of the front leg may sometimes force a slight “jerking” upward making the ball sail a little high. To correct, try focusing on keeping the QB’s shoulders parallel to the ground through entire drop and throw. You could also have QB work on “climbing the hill” on drop; or in other words, have him slowly rise during drop.
“Over exaggerating” the follow through during drills will help to keep front leg from locking during throw.
QB not getting enough “air” on deep, high arching ball (3 Ball) to WR with no defenders over the top:
Sometimes QB’s think that to make this throw they have to “lean back”, angling shoulders upward and almost “catapulting” the ball skyward. The fact is that the QB just needs to throw with a higher release point and lead slightly with the throwing arm elbow. By doing this and also following the rules of keeping shoulders parallel and following through with a slight knee bend in front leg the consistency and accuracy will be greater.
Not getting enough “Zip” on ball:
With this, there is a good chance that the QB is letting his feet get too far apart from each other on throw which causes the lower body to be taken out of the throw. If this is the problem, over time the QB will get a sore arm more frequently than he should as the throw is primarily being made with “all arm”.
The other obvious problem could very well be he just isn’t strong enough yet to make those throws. Making sure to work on the QB’s core in the weight room will certainly help with this as well.
In conclusion, even if you just emphasize “keeping the shoulders parallel to ground” everyday on every throw you will correct most of these potential problems and give the QB less to think about during drop and throw. Because we all know that in this day and age of spread, RPO, no-huddle offenses the QB has enough to think about before and during a play.
I hope this blog helps give you a starting point to diagnosing any QB issues that may arise in the future.