Wouldnt that be only for the first week?
If the person who showed up for Monday's MC gets the same EP as the person who showed up for Wednesday's MC and you dont do a decay in between, then for that week's BWL raid both their PRs should be bumped by the same amount.
I think the confusion here is between a raid week and calendar week.
When are you dong decays? Ideally with your setup you should decay after every Thursday's raid since BWL is your primary raid. This way for the next week's BWL, the people doing MC on wednesdays and mondays will get the same EP bump and same PR adjustment.
Now if you are doing a decay on Tuesday with the start of raid week, they yes, you are screwing over the Monday MC group.