THANK YOU FOR SPELLING IT OUT, HELPS TO UNDERSTAND WHAT’S GOING ON!

   Thank you! This makes sense! I too have this issue and also thought about how a baseball travels left or right (early swing or fast swing). 
  “In my head”, I thought I was releasing correctly because I’m also used to throwing a spinning rod, but my lure went left almost  every time. I was using a BFS reel, on a 7ft. UL

Mod-Fast action rod, casting tiny Ned Rigs. 
 

So, I believe this, in fact, was the issue. That is, if I was loading the rod properly. Thanks again! I’m kind of new to bait-casting, although, I’ve had a little experience before. I’m brand new to BFS, and IM LOVING IT!

Any time you're trying to cast an under-loaded rod - fishing too light weight below the rod's low-end capability - your cast windage will continue off in the direction of your rod swing.  

 

This is how you find the low-weight end of your rod.  The rod sweet spot will be the lightest weight that doesn't do that, but goes where you aim it.  

 

You get really good at this when you're evaluating a baitfinesse rod to fish 2 and 3 g, or finding the base mag set on your BFS reel.