filters = { 1: { stat: 'a' }, 2: { stat: 'b' }, 3: { stat: 'c'} }
delete filters[1]
Filters is now 2: { stat: 'b' }, 3: { stat: 'c'} }, however we need the lowest key to equal 1, the 2nd lowest key to equal 2, and so on. In the example above, we deleted the lowest key, which requires renaming of keys. In the situation where we deleted key == 3, obviously no renaming of keys would be required.
Order matters in the sense that, in the example above, key == 2 needs to be renamed to 1, and key == 3 then needs to be renamed to 2. key == 3 cannot simply be renamed to 1.