I absolutley understand impact. If you're talking about in-match, round impact, it varies from player to player. s1mple is a star player and he is put in positions where he needs to get multiple frags in order to secure a bombsite or win the round, which he routinely does basically every match. Very few players have the consistency (in terms of frags and skill) as s1mple does every match, if you dont believe me then the stats dont lie.
EDIT: And then explain to me how GeT_RiGhT and kennyS have more impact on the game than s1mple (Not saying they dont, i'd just like an explanation from you)