4Game

Currently in series 2 of ranked, players can get a total of 5 points for kills or assists.
These assist are considered when a player participates within a certain time of a kill.
With that being said this can be abused by sitting back and letting your teammates risk dying , while you attempt to tag each enemy they shoot This way you max your potential points obtained, instead of commiting to killing one enemy you are able to ensure you get credit for all three, while the other two teammates may be short a point or 2. Now this is an extreme example and not particularly ideal.

The real problem is that it will essentially inflate the points gained individually by a large amount.This will show when players don't win but are able to get by with kills, the teammate who clearly was the weak link would drop while the other teammates would continue to climb.
We must remember that killing an enemy is vital and completely eliminates the active threat, while damage done is great but means very little without a follow up.
I've had plenty games where I won a 1v3 with about 1 health. the team participated in shooting me, but no one managed to do the most important thing which is kill me.

My suggestion
Assist points are given by the amount of damage done to enemies killed by teammates, once they reach enough damage it is then transfered over to the next tier.

if a player were to get 5 points from assists only it could be under 100 damage in participation. In order to represent the progression in enemy health as the games progress:

1st point: 100 damage
2nd point:125 damage
3rd point: 150 damage
4th point: 175 damage
5th point: 200 damage

A 5 kill game where every enemy is killed upon contact (on max armour) is around 1000 damage. if you count fights where there's constant chip damage being dealt the numbers can be much higher.

Here's an example of how this will work:

Teammate A deals 180 damage to the enemy.
Teammate B dealt 10 damage.
Teammate C dealt the last 10 damage.

Teammate A now has 1 assist point and 80 damage banked for his second assist point. Teammate C Has 1 kill point, and no damage banked.
Teammate B gets 10 damage banked.

How this will work, to prevent abuse, is the damage dealt must immediately lead to a
kill. Therefore if someone is hiding behind some rocks pecking with a longbow , this system will only reward the player with what was immediately put in towards a kill, and not simply all the damage towards the enemy.