seems like it's just a waste of time to do. why after they catch the ball and grab the ball from their glove do they throw it back into their glove and take it out again before they throw it?

They do not always do this, but if you see them doing it just know that they do not have a good grip on the ball and they are adjusting their hands.

they like to hear the "pop" sound. It's a beautiful sound, really.

Just a thing, like QBS' patting the ball before they throw it

the reason they do that is to regain their balance and make a good throw...they dont throw it back in there glove they just tap the ball in their glove to make their throw in one smooth motion

I think they try to find a grip on the baseball.

to hav a better grab only

Adjust their grip on the ball before making the throw. By doing this within the glove, there is much less risk of dropping the ball and muffing the play.

Actually they dont throw it back in the glove, they have the ball in their throwing hand all the time and they hit the glove to get a good grip on the ball and to get the ball more in to the hands to have a nice throw.

So basically it's just adjusting it's grip on the ball