Read this : Vertical Casting | Older Articles and you'll see that it's a technique that's been around for awhile. Thumbs Up

Actually, I used to do that same thing ... back around 50yrs ~ ago. (when using minnows 99% of the time)
Fast forward a decade or so from that time ... and a friend of mine showed me that slowly reeling in a small marabou jig, from below the fish and up thru whatever depth they were suspended at, would cause them to "thump" that jig (when they'd ignore it if it was just dangling there in front of them)... and the fight was on !!
Fast forward a couple more decades past THAT timeframe ... and I'm learning how to shoot docks, and fish down the sides of bridge pillings. I remember doing the slow reel up, from the past experiences ... and apply it to dock posts, standing timber, bridge pillings. Well, it still worked ... and worked so well that I wrote that article, so that others could apply it to their situations .. and hopefully add a few more fish to their catch. I still use it, and it still works Thumbs Up

My thinking is ... the fish see the minnows (or jig) just hanging around there, and may be in a neutral mood, so they don't show much interest. BUT, let that minnow (or jig) "appear" to be leaving the scene .... and the fish react, so as to secure the "food" they know they'll have to go find, later. It kinda snaps them out of their neutral mood, even if only momentarily. And sometimes, it can even trigger a feeding frenzy ... since fish can sometimes act like greedy little kids Rofl .... that have the "he got one, where's MINE" attitude !!

... cp