Our 2010 Jayco has the non-adjustable version of this awning. it does suck. Mine is not as slanted as yours is, because mine is mounted on my travel trailer, I guess they make the angle different? Mine goes straight out parallel with the ground, no slant.
When it rains, I take a LYNX leveller block and wedge it between the bottom most part of the arm and the arm above it, this puts a bit of a sag in the awning and forces the run off to go to the back of the trailer. If I don't do this, the "auto dump" feature can be very surprising as you have no idea which way it is going to dump.
2010 Jayco JayFeather 213 EXP
2016 Ford F-150, 4x4, 3.5L ECOBOOST, MaxTow, Supercrew, 6.5FT, 3.55 axle