I think if you keep your left arm straight your club will end up where it should be, as long as you don't over break your wrists. The angle of descent in my opinion has to do with how flat or upright your natural swing is. The shoulder angel and hip rotation angle can determine this. I'm no pro but i try to keep the game as simple as possible, i make full swing adjustment by bending my knees and/or changing my upper body angle to the ground. If you are stuggling on striking the ball, you should check your clubs fit to your swing, if your swing needs work then get a video lesson so you can see what is going on. Once you have a solid repeatable swing and have fit clubs to it, you should see results and establish a baseline. When you deviate from it, because that's what we all do, it seems easier to get back to the baseline with some practice.