From my experience it does. And it's not that I don't play well... I often go in there for a warm-up and typically play quite well, though of course being human I have my bad games as well. But it is undeniable the frequency of weird things that happen in Core as opposed to HC for me.
So please don't feed me any lines about staying on target. Please stop with that arrogant take. It has nothing at all to do with that. The undeniable fact is... in Core the weapon you use matters more. It is hard to deny that you have a distinct advantage in Core using certain weapons over others. In HC this a factor as well, but all of the weapons have an equal chance of success. I will say this CoD has more balanced Core play than in past games, but its still there. I just find any lag or latency issues far more evident when playing Core, and while they are present in HC as well, they don't seem to be as big an issue for me.
I play in Core to warm up to get my aim on point, then play HC afterwards. I feel like it gives me an advantage when I get to HC because I am more likely to stay on target and not count on a random spray to kill an enemy.
I hear the Core argument claiming HC players can't "stay on target" and that is why they play HC. Complete nonsense, though of course there are exceptions both amongst Core AND HC players. You HAVE to be accurate to be consistently good in HC. While yes, you MIGHT get a few lucky kills, a more accurate, tactical player is going to consistently have success. I find in Core modes my HC experience is often an advantage. Many Core players don't move around the map tactically, rather they boost jump and wall run and blitz through open spaces without care, knowing their Health Regen will help keep them alive. I often am able to take advantage of this when I play Core as I can anticipate their movements and get the jump on them easily.
The fact is, there are talented players in Core, and talented players in HC. There are bad players in Core and bad players in HC. It's more a matter of preference than anything else.