My explanation for 6-60 year olds.
The bridge theory. The SF Bay bridge is closed and the closest way to get to Oakland from SF now is the San Mateo bridge. Down the peninsula, across the SM bridge and back up to Oakland.

It takes longer,takes more energy and more tired when I get there...but..I get there.

the other analogy is the cellphone. sometimes you are in a good cell and reception is great. sometimes the call drops Same with MS sometimes the connection is good.other times not so good

hope this helps