Claymores past their sell-by date (and grenades)

We've all seen actual footage shared on YouTube or social media of a player sitting in a corner; an enemy comes around the corner with an rpg to aim it at the tank up the road, only to discover the tank has moved; they see the corner camper, and fires the rpg, rather than attempt to swap weapons and risk being killed... and he dies anyway, because the rpg has no splash damage.  It's ridiculous.

But lately I (and my pals) have seen claymores which have been sneakily placed, and either we have walked through them, or the enemy has, and you're wondering 'how on earth did that claymore not go off?'

And it's not just out-of-date claymores, it's grenades as well.  Playing last night on 'Contaminated' as defender, we had been beaten back to the penultimate set of capture points.  There was a relentless barrage of players trying to take the B point, which lies within the outer compound of the base (the final point is in the base), and I was guarding the side nearest the base.  I noticed several players were pouring through the gap in the wall on that side, so got to the edge of the map, giving me a good view. 

I took out maybe 5-6 players, then one guy appeared, who lay down in a crater about 15 metres in front of me.  I threw a grenade, and watched as it landed about 2 feet in front of him. Certain that was him killed, I relaxed.  The grenade went off - I didn't even get a hit marker!!  The player stood up, and one shot killed me, with a DMR, which in itself is peculiar because even my SVK needs two head shots, and his was a M39 EMR.

That aside I'm curious how a grenade two feet away from a player doesn't blow him to kingdom come.  The only thing that comes to mind is that 'blast damage model'.  Is it a case that blast damage is programmed to go sideways and upwards?  Since he was in a crater, he was lower than the level of the grenade - only by inches mind you, but it is very puzzling that he survived.

And as for claymores - I think EA needs to order a new batch, because these ones are past broken