Just understand that Smith, nicknamed "Cowboy" and referred to as "a John Wayne kind of guy around our building" by Harbaugh himself, has been playing that way for a long time.
That play headlines our weekly list from ESPN Stats & Information singling out the five plays with the greatest impact on win probability. Four of the five most pivotal plays from Week 4 involved NFC West teams. Those and one other -- James Laurinaitis' interception for the St. Louis Rams -- appear in the chart.
Note: These calculations, provided by Alok Pattani of ESPN's analytics team, reflect results from thousands of game situations. They aren't perfect in part because coaches approach specific situations differently, particularly in close games, but the general idea is sound.