When searching for secondary in drafts there is no way to know how good or potentially good/bad a defender is at pass knock downs, and as this is a passing league think that this should definitely be added.

Shouldn't that be controlled by the coverage attributes mainly? Those might just indicate how well they stick to their man or play the zone and have no effect on knockdowns other than making sure they are in a position to make the knockdown though.

Yes, that's essentially how it works now - there is no 'knock-down' attribute, only attributes that place the player in a position to execute a knock down. Another attribute to consider is 'punish receiver' which works against the receiver's courage attribute to knock the ball out as he is catching it.

Whether the defender decides to try to knock it down is dictated by experience. He will either decide to "make a play " or not.

Combine that with his actual ratings and you will get an outcome.

Young guys might go for an interception and miss while the vets will sit back and just knock it down.

Both play in to the favor of the vet, but do you want a knock down or an interception? I guess it depends on the situation, but in general the vet will pick it off more, and the young guy will knock it down.

When the QB is under pressure those numbers go through the roof.