If that was the case, when they fought, Superman should have been down with the first 2-3 punches.
Maybe Captain Marvel doing so well against Supes has something to do with his strength. Considering he and Superman are equal. As well as his durability. Considering that Cap's durability is argueably better than Supermans.
Superman nowadays is not as vunerable to magic as he once was, yet Cap still does just as good against him as he ever did.