Bumgarner does. He may not go quite as far as most down the mound but he does. Kershaw does not at all. But if you look at the vast majority of mlb pitchers they do. I understand that in theory you could glide that foot right down the slope and get just as much speed, just as long a stride and do just fine. And I use the word theory cause most hs pitchers will cut their stride short and slow their core when they do this. Clearly I understand with a kershaw it is more than theory it is reality.