Most people do plyo wrong. Mainly, they forget that they need to absorb the shock on the landing. That's where many of the benefits come from. Plyometric push-ups activate the fast-twitch fibers in your chest, shoulders, and triceps.
To perform the depth plyo push-up, you're going to start from a higher position, land lower, then project yourself as forcefully as possibly.
Set up a couple of short boxes or stacks of plates. Make sure you have room to place your hands correctly in the landing position. Start with your hands on the plates.
Drop to the floor, catching yourself in a 90 degree elbow position. Immediately explode back the plates.
When you land on the plates, pause and reset on every rep.
Dan John wants to know if you're making progress. It seems the answer should be simple, but is it? Fortunately, the big guy offers up 3 unorthodox ways to gauge your answer. (Wait until you read about the "pencil test".)
High intensity vs. volume training. Olympic lifting vs. powerlifting. High intensity cardio vs. low intensity cardio. The list of debates and disputes in this field goes on and on, and perhaps the most disputed area is abdominal training.