I should explain that I'm definitely no expert on tertiary admissions and could have it all wrong, this is just my thinking.
Aside from exceptional circumstances affording special consideration the only explanation I can think of as to why 9.33% of offers made were to students below the clearly-in ATAR is that their aggregate points from Year 12 studies pushed them over the line and above your ATAR. That is, if those students are still statistically considered to have ATARs below the clearly-in requirement.
Taking this into consideration and the fact that you didn't get a first round offer indicates to me that UoM had no difficulties finding enough students for their BSC with ATARs above the clearly-in figure which suggests their second round offerings will be pretty competitive. Assuming there are second round offers for the course (and I do assume there will be) you might be in luck considering your ATAR is 1.35 above the clearly-in figure, which could be enough. Keep your fingers crossed, so to speak.
Until then I suggest you do everything necessary to enroll yourself in the Monash course, since you can (I believe) withdraw if offered a second round place at UoM and if you don't set yourself up at Monash you'll be left with nothing.