Given the clear data pattern that MWM events that don't require having a particular deck tend to get more participation, isn't it possible to interpret the MOMIR data as there is low barrier to entry so people will play the event to get rewards in spite of not actually enjoying the event? Is it possible that in such a case that engagement may not be the best measure of the success or enjoyment of an event? Support of the hypotheses that people are playing for the rewards could come from examining whether or not people continue competing for wins past their 3rd win, or examining polls of whether people had fun this match. Lower probabilities of enjoyed given win and low probability of fun given loss would be an interesting comparison to other events if you haven't already looked at that.
Thanks for participating in the forum and giving us insight into the decision making process!
As you bring up, there are a variety of ways to measure the "goodness" of a MWM event format. Allowing more players to play is one way to do that, and Momir excels there. Behaviors like playing past rewarded wins (indicating enjoyment) are also good, and that tends to come from events that require unique deckbuilding constraints (that also get much lower participation).
Basically, different formats drive different types of positive experiences, and that's why MWM offers a variety