Mid year considers both ATAR and uni marks. I'm not sure if the exact weight has ever been explicitly stated but i would put it at 50% (plus or minus about 10-20%). I doubt it would be any more crazy than that.
Your uni marks are a much better predictor of how well you'll do in a university environment compared to your ATAR, they are also more recent. This is why universities prefer them.
By the end of your first year, ATAR wont be much of a consideration to them. Mid semester, they will consider both.
Just make sure you'll be happy to stay at Deakin or La Trobe if you can't get out. I know so many people who had hopes of transferring out but never got the marks. Everyone thinks it wont happen to them but its best you seriously, seriously plan like it just might happen to you.