This may be a bad example, but look at Tim Tebow.
His arm is very below average, certainly not NFL caliber, but he makes up for it in other areas (mobility, toughness, leadership), which makes him serviceable. If he was not mobile, he would not be in the NFL, and most likely not a D1 college QB.
If Obekpa wasn't such a great defender, he's be looking for a D2 school or JUCO to play for.