So I have had this swing problem for as long as I can remember until last Fall I think I got it taken care of. I started swinging very very well in February, (left leg extended fully at impact and then hurt my lower left back somehow, then my swing went to crap from there. I was too shut at the top, and too flat. I am getting better with this but it took 6 weeks for my back to heal up. I don't know if the thing caused me to swing differently which introduced bad habits but now I am not nearly as fast as I was in CHS back in february, I am getting better, but not close yet. I am also hitting the ball with a low hook usually or just a low straight shot. I know I was doing this partially from being shot with the club at the top which I've pretty much fixed, and starting to hit a bit higher. But, I can see in my shadow that right at impact, my left knee goes foward to the target right at impact and collapses almost like I am not clearing my left side. In my practice swings I don't do it at all. But even with a pitch shot with a wedge it happens, and I have poor impact. I can sit there and hit for hours focusing on just extending the left leg at impact and make no progress. Febrary I was hitting a slight draw, 15 degree launch angle, good spin numbers and my BS average was about 172 and CHS 116mph. Flying it roughly 285 at sea level, now I am barely flying that at 4500feet elevation.
Any drills or what might be the cause?