Taylor has a point - a good one. If there is a lot of lube in the patch, it will also be beneath the ball in the patch wrapped about the bottom surface of the ball. As the ball is pushed down the bore, lube will be left on the bore by the patch, and I suggest that through capillary action, lube will be sucked up by the tight patch fit in the grooves and will 'feed' the contact between the ball and the lands.
If this was not happening, you would likely have what would amount to be a dry patch, after not very much ball movement down the bore. I do think lube is (sucked is not a good word here) transferred up to the ball/patch/bore contact surface and continues to feed this area & is therefore deposited onto the bore & in the grooves - IF there is indeed, enough lube in the patch.
If the patch is too dry, you will lose this lubrication and thus, 'fouling softening' action of the lube after the shot as well.
I've noticed in my 48" barrel, that there is sufficient lube to shoot 'cleanly' even with patches that are on the thin side of my preferred fit. Same with the .36 and er 38" bl. A patch that is easily pushed in to the bore with a choked up loading rod, shot cleanly for 3 hours of constant shooting last Tuesday. I figured my rifle fired perhaps 80 to 90 shots. No wiping was ever needed nor did I have to use a starter. I was shooting a .350 ball, .018" patches in a Rice barrel, square grooves and 43gr. of 3F GOEX.(because that is what the measure I used, threw)
This was a high school teacher's day at the range. We had over 40 of them, shooting small bore, big bore, trap, and cowboy action as well as my flinter and a friend's .58 S. Hawken.
We also gave them a history lesson - it was all very well received.