These are all the official counters for ACS in Valorant:

Damage: 1 point each

Kills based on enemies alive: 150/130/110/90/70

Multi-Kills: +50 per additional kill

Non-damaging assists: 25

Just by looking at this assists are practically worth nothing, besides damage assists, and even then you aren't getting much compared to the person who actually gets the kill.

Lets take an extreme example:
2v5, you have a phantom and you miraculously dink all five of your opponents for 140, without killing any of them, and then your teammate clutches with all leg shots run and gunning with a spectre only doing 22 damage each. Lets do some math real quick. Your combat score for that round for damaging all your opponents is 700, pretty good right? Well your teammate, who didn't even really do anything, gets 860 for just running around spraying their spectre.

See how in this extreme example it seems a bit unfair? Well you might say something like "Well that's such an extreme example it doesn't even matter!"
How about a normal encounter that I'm sure you've seen happen all the time:
You wide swing an angle at the beginning of the round with your teammate, you headshot someone for 140 and your teammate body shots for 39 (Both of you have phantoms), your teammate gets the kill gaining 189 combat score for the round while you walk away with only 140 for damage done.

Now this isn't something most people care about but the real problem is when it comes down to the non-damaging assists. As a support player myself I sometimes can rack up 15+ assists for a game off of my smokes/flashes/heals etc. while not fragging out too much. It can lead to at the end of the game I'm at the bottom of the leaderboard and my supporting role going fairly unnoticed.

A way to fix this without taking too much away from kills being the biggest contributor to combat score I feel should be to award the player who got an assist 50% of what you would normally be getting for that kill and 25 points per additional assist per round.

I would make a new ACS calculator that looked something like this
Damage: 1 point each

Kills based on enemies alive: 150/130/110/90/70
Assists based on enemies alive: 75/65/55/45/35

Multi-Kills: +50 per additional Kill
Multi-Assists: +25 per additional Assist

~~Non-damaging assists: 25~~

This will encourage players to learn how to use their utility well and for their teammates (Looking at you Initiator mains) but will still award players for high frag games if they just happen to pop off.

And to call back to that original extreme example. The player who did all the damage now gets 1075 combat score for the round better representing the impact that they had for that round. I would much rather see a Brimstone as Team MVP with a KD of 10-10-28 rather than them at the bottom and a Reyna insta-lock Team MVP at 23-17-2.

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TL/DR:

The ACS system needs to be reworked to award more teamplay instead of just awarding high frags, it's part of the reason why people insta-lock duelists.