Cahill struggled in their Champions League defeat at Napoli this week.
"Gary speaks a lot and organises the defence. I think it is just takes time as a new partnership to get used to the person next to you," said AVB.
"[Cahill] has played the games he has to play and is doing excellent. I am very happy with his performances. In the beginning, if he was first available for Norwich with only two training sessions, then January was our best defensive record statistically, so we didn't want to shift the dynamic of the team, and he eventually had his first chance against Man United and did extremely well and has been doing since then."