This isn't a criticism, because using the votes from every individual list from 10 years' worth of this event would be an absurd amount of work, so can totally understand why you just went with average rank. But using average ranking alone has produced some strange results, like Fire Emblem: Three Houses getting a higher rank (#29) than it achieved in the one year it was available for voting (#30). Same with Smash Bros. Ultimate (#15 but 'only' managing #17 in its first year).
A suggestion for the future to remedy this would be to allocate points to each position each year. For instance, a 100th position would be 1 point, a 1st position 100 points. Add all the points up and rank them from there. Might be some extra work, but I don't think it's much more, if any, than what he did already for this ranking.