GBFavreFan wrote:IAs for being like John Elway, Elway was a lumbering oaf with the agility of a crippled cow, and it wasn't even physically possible for him to slide feet first.
You might want to look into Elway's history a little more. For most of his career, Elway was an agile, athletic QB who was considered a serious running threat. If I'm not mistaken, he's ranked 6th all-time in rushing yards by an NFL QB. He ran for over 3400 yards and 33 TDs, not the numbers of a "lumbering oaf with the agility of a crippled cow".
Regarding the thread question: I think it's entirely dependent on the circumstances. Diving feet first works best if there's sufficient space in front of the QB. He can get to the ground with little concern about taking a big hit to a vulnerable spot. However, in closer quarters, without sufficient space in front of him, sliding feet first leaves the QB's upper body more vulnerable to a hit. That's probably why Musgrave is suggesting head first dives in some situations. It's perfectly logical. It gets the QB's head and shoulders down, pointed toward the ground, covers the ball and overall, make his most vulnerable areas (head, shoulders, ribs) less likely to be hit.
Either way, the idea is to get down before getting hit. Musgrave is not suggesting Ponder stick his head out to absorb a blow. He's telling him to get his head down. It's probably slightly easier to do when running anyway because it allows the runner to use his forward momentum.
RBs put their heads down and initiate contact all the time and they rarely suffer injuries to their head or upper body as a result. Ponder isn't even trying to initiate contact. he's just trying to get to the ground quickly and avoid contact. As far as I'm concerned, any way that's accomplished is good.