Why are some traffic coming with no referral link. One would be that the page might have been bookmarked, what other possibilties are there?
Type-ins, someone blocked sensitive data being broadcast by means of AV software, firewall software etc. I think links via redirects lose referer data (not sure though).
In statcounter, even email referrals are also shown.. One can say if it is direct access, there wont be any referrer.