Shanahan said he wasn't thinking about going for it on fourth-and-4, and that's where his mistake came in. On third down, the 49ers came out in 11 personnel (one running back, one tight end and three wide receivers), and the Chiefs matched with their dime personnel package (six defensive backs). There wasn't even a pretense of running the ball, as Purdy lined up in empty and had
Christian McCaffrey move across the formation in motion.
The league's most aggressive fourth-down offenses gain an advantage on third down by being willing to run in situations where teams typically throw the ball. Third-and-4 (or even longer) can be a run down for the Eagles, Lions and Ravens, because they're comfortable either picking up the first down or going for it on fourth-and-short. In 2023, on third down with 3-to-5 yards to go in games where each team still had at least a 20% win probability, Shanahan called 16 passes on 17 plays. The Lions called 29 passes on 39 plays. The Eagles called 24 passes on 41 plays. Purdy isn't
Jalen Hurts, but the 49ers have a great rushing attack, and the Chiefs aren't a great run defense, even if they were better than expected against San Francisco.
Shanahan has run on third-and-long before, with
Raheem Mostert's
third-and-8 trap against the Packers in the
2019 NFC Championship Game as a famous example, but if he wasn't thinking about going for it on fourth down, it had an impact on his third-down call. Running the ball on that third-and-4 could have converted on its own. It also could have set up a fourth-and-short that would have tipped the scales toward going for it and potentially converting for a touchdown. The bigger issue with what happened on third down was the pass protection, but if Shanahan was more open toward going for it on fourth-and-short, the 49ers would be a more dynamic offense on third down. Without knowing how things would play out, the 49ers probably would have been better off running on third-and-4, especially given how the Chiefs matched with their personnel.