^^ The tanks were not unsupported, I think the Free Syrian Army militias were meant to support them, or rather: the tanks were meant to support the militias. Unfortunately the Free Syrian Army in northern Aleppo consists mainly of young boys having barely any military training, being not on par with ISIS at all, though being peppered with a couple of veterans.
Military situation in Syria after start of the ceasefire, December 30th, 2016.
Extra:
Despite being bombed on the road between Raqqah and Al-Bab by the turkish airforce, ISIS reinforcements arrived at Al-Bab, Syria, December 29th, 2016.