A bit of my theory here.It's never 5 in first place. It is 5.5 to 5.9
I think that number is closer to 5 than 5.5. Assume that majority of the candidates go through WES before creating the EE. The standard time for Wes evaluations is 2 months. However in late feb due to some reason Wes said that the number of applicants had risen and hence they sounded out to all applicants that the standard time of evaluation post acceptance of documents has now been increased to 35 days from 20 days. my own evaluation took 3 months and I received the same a week ago.
Hence the spurt in 451+ could be because of this backlog.
I believe that the number of 451+ was very close 3350 this time and very very few slots were left for 450 candidates. Hence the ridiculous tie breaker.
Now since the Wes backlog has cleared and now I sense that they are back up to speed on their evaluation, the number of candidates entering the EE pool will also normalise.
So, 450 folks keep your chin up and next draw will surely bring back the normal cutoffs back. All the best!