Sometimes the best offense is a good special teams unit.
That's a great play right there. A lot of players are taught to go for the strip in a situation like that. Once the player is going down or being tackled by your teammates, the defender should go for the ball. Great execution by the Lions on that play, something that will make Jim Schwartz happy.
The 49ers defense is very, very good so starting with the ball on their side of the field is a major bonus. The Lions weren't able to fully capitalize on the series but still kicked a field goal to make it 7-6.