Leg Press? The Sled? Where you push a stack of plates up at a 45 degree angle? This doesn't work near the amount of muscle groups as Squats and Deadlifts. Do you isolate all the muscle groups you've missed? In my experience and from what I've read, Leg Press is one of the most injury causing machines ever. I'd have to agree as it puts a lot of stress on the knees. You don't have to stabilize anything, so it only really works quads and glutes. You can go heavy as hell because you don't have to stabilize anything, which seems to me that it's going to build your muscles imbalanced. Not to mention it rocks your knees horribly.

Supposedly there isn't anything wrong with Squats and Deadlifts if done correctly...