a lot of DVOA is based on first downs. some quotes from football outsiders:
"On first down, a play is considered a success if it gains 45 percent of needed yards; on second down, a play needs to gain 60 percent of needed yards; on third or fourth down, only gaining a new first down is considered success."
"Imagine two running backs who each gain three yards. Player A gains three yards under a set of circumstances where the average NFL running back gains only two yards (for example, third-and-1), it can be argued that Player A has a certain amount of value above others at his position. Likewise, if Player B gains three yards on a play where, under similar circumstances, an average NFL back would be expected to gain five yards (for example, second-and-15), it can be argued that Player B has negative value relative to others at his position."
so, their DVOA stat reflects this, and is much better than traditional stats which treat all yards/Ds as being equal
if you want to measure "explosiveness", I dunno, I think Drive Stats come pretty close to this.
Yards/Drive, Points/Drive, TD's/Drive, Punts/Drive, etc