Using a poly instead of a more substantial tip on a skagit head results in a monster download of energy right into the base of the poly. This can cause premature turnover/ abrupt turnover- far too powerfully to be smooth. It can cause bullwhipping, 'wind' knots, all sorts of crap including loss of distance.
Try a scandi head in the same grain weight with your poly, or a more substantial tip on the skagit. You can also back off the gas on the forward cast and try a super high stop. Make sure your bottom hand input is smooth.
Whatcha fishing for, snook?
Captain of the Jameson Godawful casting team
Sportkilt Sponsored Middle Aged "athlete"