I got this issue when I bowl in league. When I bowl practice games I can never get any movement on the ball It stays flat or mostly flat but when I get to league night the ball will take off like a rocket! It doesn't seem to matter the conditions of the lane b/c I've looked at the ball and each time it looks to be covered in oil, the Track is quite visible I mean. So is there any way to tell what kind of action I'll get before I let go of the darn thing?

This game is just like golf... You feel like you're doing the same thing over and over and you get radically different results! still more fun than golf though...

That is why you generally get a practice ball before league, to see what the lanes are playing.

Are you sure your ball isn't acting normally on oil by hooking? It could be too dry, and it rolls out in practice.

well some times it goes flat on the first ball and then rockets on the second with the same ball, same frame, just the second ball!

There's a chance there is a ton of carry down when you practice. Open bowlers may have bowled on the lanes before you throwing straight balls thus pushing the oil to the backends. This can cause difficult lane conditions. Whenever I bowl against a group of old ladies that throw straight balls in league I always have a tough time with keeping up with the lane transition.

There could be numerous things that could be at work here. I'd suggest shooting some video of yourself to look for some discrepencies in between shots. Your ball speed or rev rate may change between practice and league. Like Dennis said, the patterns may change from practice to league. In practice you may have to deal with more carrydown or things like that whereas in league you may have a stripped backend to allow the ball to react on all that dry lane.

In summary, ask the desk and/or mechanics about the conditions, and shoot some vids of yourself and look for things that change between shots.

They probably strip and oil before league, the fresh backends is probably what you are experiencing.

I agree with Demo-guy. That is too radical of a change between 2 balls. Sounds like you are doing something different on each.

You could be over compenstating with more hand the second ball due to lack of reaction of the first ball and or accuracy hitting your intended mark. Use to be a problem of mine until I began to understand lanes transitions. Once I did, I was able to adjust and play my game effortlessly. I still have issues with carrydown, but its much better than it use to be.