The initial set of 1922 data points is really, really weird.

When I'm analyzing a time series of binary data I like to look at how that data is distributed in time, to see how randomly the data points are distributed over the set. An example of how to do this is starting with the first crit, count how many attacks it takes before you see another crit. If the algorithm was perfectly random, you'd expect to see consecutive crits about 10% of the time, a single normal attack between crits 9% of the time, etc. In the initial sample we have 157 crits, so 156 crit pairs, which we'd expect to have a distribution of:

attacks before next crit: number of observations

1: 15.6

2: 14.0

3: 12.6

4: 11.4

5: 10.2

etc

What we actually saw:

attacks before next crit: number of observations

1: 1

2: 37

3: 3

4: 1

5: 1

Needless to say, that is an incredibly odd result. The entire set is like that, and there's no smooth function for generating random results where that isn't an incredibly odd result. Something is clearly wrong with the way Riot is generating crit results.