I guess the main issue with high backlifts is they leave you vulnerable to being beaten for pace. We've had all time greats with huge backlifts, but they're not the norm. The angle Hay's bat comes down at is also something I've been thinking about since he has to rotate the blade and get the bat down quick enough to close the gate. I'd be interested to know how he handles an inswing fast bowler like Adam Milne in the nets, and in a match situation as soon as Hay came in I would get my inswing or fast bowler on. But hey (Hay), maybe he will prove he is one of those special few who can get away with it (he definitely can in the Shield). He wouldn't be the first or the last and he has good footwork which is essential if you're going to have a backlift like that so you can at least get decisively forward or back (CdG springs to mind as someone with a Hay-esque backlift but poor footwork).