Texas & EC,
Sounds like your both talking similar points, but just expressing it differently. Perhaps this is the problem that the OP is having with the academy & the coach-although I strongly disagree with the bent knee.
Some food for thought:
1). The best swing is the one that allows you to adjust to the pitch that is thrown.
2). Considering #1, each swing will have some variation, however big or small, which leads to the finish not always being the same.
3). Finish often has more to do with a hitter's style than the substance of his core mechanics.
4). Still photos often only tell a small part of the story. You don't see the point of contact, what happened just before, just after. etc.
5). If analyzed with frame-by-frame video, you will see that most all MLBer's have a firm front leg right around contact, some for longer than others, also a product of the pitch. BTW-Chipper Jones is truely a great professional hitter. That was not one of his best swings. He actually got jammed, but adjusted mid-swing and was able to muscle the ball back up the middle.
6). MLBer's can and do occasionally hit a ball well, even a HR, when fooled, or not having the "perfect swing". The pitching is pretty good up there, you know? But they are the best hitters in the world, big, strong athletes in their prime, it's going to happen, but that doesn't mean that it was a good swing. If it was then why do they not swing like that all the time?
JMHO.