This is going to make me sound like an ass and an elitist, but also consider Ser610's profile. 700+ GMAT, 3.9 GPA, 6+ years experience at a global company, and I'm going to assume he/she has got outstanding essays.
That is a rock star profile. That goes to the top of the list.
Yes Leigh might have been touring South America, but with her very limited time she's only going to pick the top profiles; she's definitely not interviewing by who applied first.
Had Ser610 applied earlier, they might even have been invited to some Rotman events to get them to come to Rotman.
Also, I apologize for not knowing this: do international applications close earlier than Canadian applications? Round 5 is still in June...