Depth Chart question

[Hubbard]

I have eight OL on my team. When I go to the depth chart/formation view to set the depth chart I have three OL available for back up. Since there are 5 starting OL, only 3 OL are available as backups. That means 2 OL will not have back ups in the depth chart. In fact, those 2 positions show the starter and the 2 back up slots show " 0 empty".

My question is how does the game sub a player if there are no back ups in the open slots of the depth chart? The depth chart does not allow the 3 back up OL's to be used in multiple positions easily. I have found a work around but it is time consuming.