Injury ratio is not the problem in this case, although 68 is higher than I would set it for preseason were it up to me. The problem is the cluster injuries, all 3 centers and both TEs. I have a higher standard to play in preseason, anyone with an injury designation sits unless I know I'm cutting them.
That being said, only 3 of the 7 would play if this were regular season. Two of my 3 centers would be active so I'd be fine there, but I'd have my FBs playing TE because they both are under 60% health.
I'm really just complaining to blow off steam and to alert any game engine nerds that might want to see the game engine's substitution patterns in this situation.