Everything from injuries, to the number of penalties, to the number of challenges, to the number of booth reviews, to the number of turnovers, to whether one team wants to predominately run the ball or go fast determines each game.
I can't imagine that Detroit wants to go fast. The last thing they want is to get into a scoring contest with the Rams. If KC can't beat the Rams that way, the Lions surely can't believe that they can.
So I expect Detroit to want to grind it out, ball control on offense and play a lot of soft zone while playing the run first on D. They are going to want to be physical and see if they can get the Rams to lose their cool (like the Seahawks do). Goad the Rams into some personal fouls.
I don't think it'll be very pretty or artistic.
