The off-hand fingers should work in sync with your shooting hand. The idea that the off-hand should come off the ball and not influence the shot is false. Your fingers on your off-hand should be pointing at the basket at the end of your release. 
The reason why is the width of your palm is less than the length of your hand. 
What this means is that when you point your finger towards the rim during your release you increase the surface area in which your hand is guiding the basketball towards the rim. This will improve your ability to keep the ball straight. Step Curry pushes the ball with his thumb adding to the consistency of his shooting motion as well as adding extra power to the shot. You don’t want to have your fingers on your off-hand pointing straight up during your release. The reason why is it decrease the surface area that the shot can be guided towards the rim & because of SHOT UNIFORMITY. No other shot do you teach to keep your off-hand fingers point straight up. When you shoot a layup your off-hand is typically pointing towards the rim like so…
or guarding your body similar to shooting a hook shot. 
Now let look at the off-hand when taking a fadeaway jump shot. 
last look at a layup in a wheelchair 
When we look at the off-hand in comparison to all types of different shots we see that the off-hand fingers aren’t pointing upward that in reality they are pointing to the rim or shielding the defender. Look at these shooters off hand. 
Ultimately the most import aspect with your off hand is to have your finger pointed at the rim. I advocated 2 approaches to teaching players, a non-thumb push and a thumb push approach. The 1st approach incorporates no off hand interference or thumbing of the basketball. This is best achieved through the use of a training aid. The one I recommend it Jay Wolf’s shooting Strap.
The 2nd approach is incorporates pushing the ball with the off-hand thumb.(Steph Curry Approach) Many great Player thumb the basketball, players such as Steph Curry, Reggie Miller, Larry Bird, and Ray Allen. The genius behind Curry’s shot is that by tucking the thumb with the off-hand you add power, but more important you add a consistent and repeatable shooting motion for your off-hand. You also create a synchronization with both shooting hands working together moving towards the target.
Both approaches have you turn the off hand fingers towards the rim. With one slight difference one incorporates a thumb tuck and the other has no thumb interference what so ever. Both are effective and come down to personal preference.
I Primarily use the no thumb interference when teaching new players how to shoot. It is simple and with the use of the Jay Wolf’s shooting strap very easy. For other players who want an alternative approach tucking the thumb can make more sense in the right situation. This technique is generally reserved for players who already have thumbing issues who reject the strap and are seeking a different approach. For the overwhelming majority of players going with Jay Wolf strap will be the best choice.
Another aspect of your off hand is in the relationship with shooting hand. The shooting hand and off hand are connected and work together as one. Newton’s 1st law of motion- every action has an opposite and equal reaction. When you hold the ball on the side then rotate the shooting palm. The equal & opposite reaction is to rotate the guide hand in unison so that the off hand is on more of a top position.
In regards to shot uniformity, the off hand moves the same as other types of shots. In a underhanded free throw the off hand rotates with the shooting hand to the top of the basketball fingers pointing towards the hoop. On a layup and sky hook your off hand moves to shielding a defender. Your off hand doesn’t stay motionless it moves with the rest of the body. Fade-away, free throws and Jump shots all have the same benefits.
- Works in unison with your shooting hand by rotating.
- Ball security—you have more control over the ball anytime you can hold it from opposite sides.
- Shot Uniformity—-in regards to every other shot, your off hand moves and does NOT remain motionless.
- Shooting is a two handed, full body shot.
Thank you to Impossible Training
Micah Lancaster @micah_lancaster
and
Bryce Stanhope @brycestanhopealong
and
Kim JU AN Bradley @globaljumpshootmotion