Average speed at the LOS is a ridiculously stupid stat. Zeke has lost speed, I'm not denying that, but an RB shouldn't be hitting the LOS at a full sprint.
Look at your most common run plays. In outside zone, you're supposed to read the defense as it flows laterally and you don't accelerate until you find the cutback lane. On an inside or zone duo play, you actually want to press the LOS and play it kind of slowly to force the LBs to commit, then you cut back to where they aren't. Power/pin-and-pull type plays reward raw downhill speed more than zone does, but you still need to be patient and follow your lead blocker until he hits the kick-out. In none of these situations is a running back supposed to open the throttle and show off his maximum speed.
The only time I can think you'd want a back heading towards the LOS at full speed is on a stretch play where he's trying to get to the edge ASAP (and that's assuming he has a clean path to the edge), or when the OL immediately blows a huge hole open in his assigned gap and he has a straight shot to the second level.
As others have said, it's exactly like the QB ball speed metric. Intuitively it seems like a good way to measure arm strength, but the problem is that QBs aren't pitchers throwing fastballs. Even for deep passes, throwing a flat heater is BAD. You want arc under it, you want touch, and you want a QB who can mentally "see" how the safeties will react when they see the ball thrown - so when you get down to it, max speed is pretty much useless. Deshaun Watson has one of the worst "fastballs" in the NFL per the radar gun and he's probably top 10 in the league at deep throws.