They could easily identify the worst hackers just based on the game play data without needing to actually confirm that they have cheats installed.
Snapping between spread out people to get a half dozen head shots in a quarter second? Hacking.
Locking on to someone behind a wall? Hacking.
Hacks that nullify recoil? They should be able to tell by unrealistically precise counter movements.
Sure, games can occasionally have network issues that result in these kinds of things but if someone does it regularly then it isn't a networking thing.