They didn't stop the 49ers offense at all. In the first half when they only scored 6 points, that is true, but they only punted once, which was on their first possession and was because of the holding penalty more so than defensive prowess. The 49ers had two turnovers and two trips to the red zone that resulted in FGs instead of TDs (and one of those was because of the time on the clock) on their other 4 possessions.
That isn't schematic prowess. That is the 49ers bailing them out.
I call holding a team to six points and getting two turnovers "stopping them". The Niners looked extremely frustrated by the end of the half.
You can disagree with the terminology, but that's my take.