After weeks of pulverizing opponents into submission, the San Francisco 49ers defense suddenly sprung a leak. Until the Thursday night game against the Arizona Cardinals three weeks ago, San Francisco hadn’t given up more than 20 points all season. As recently as Halloween, Football Outsiders’ numbers put them in generational company as an all-time great unit. Now, after three straight games allowing 24 or more including the team’s first defeat, questions arise about the long-term viability of this group as a dominant force.
FiveThirtyEight’s Josh Hermsmeyer wrote about the variability of defense last January before the Super Bowl, pointing to its volatility and unreliability as a predictive metric.