Stupid question: why the third slot?

I mean the one on your left, where your Watchful etc. are displayed…
So the first is for the stat, the second is for the second chances, but why the third? You can click it and it loops you back to the main page. Maybe there used to be something here? Or in the future?

Some stats have more than one kind of Second Chance! Over the years, new kinds have been introduced and old ones phased out - the extra slot provides room if you happen to pick up some of the old ones as well as the current ones.