The 49ers' win over the Dallas Cowboys in the divisional round of the playoffs was one born largely of their defensive players' ability to read the game, which will come under even greater scrutiny on Sunday as the Niners look to return to the Super Bowl with victory over the Eagles in the NFC championship game.
San Francisco's defense limited Dallas to just 12 points last Sunday in a game in which its back seven enjoyed one of its finest performances of what has been a tremendous season for DeMeco Ryans' unit.
Throughout an extremely stingy showing against the Cowboys, several key players on the 49er defense allowed San Francisco to excel on that side of the ball through their tremendous eye discipline and success in diagnosing the game.
One of the Niners' stars in that regard last week was All-Pro safety Talanoa Hufanga, who has been regularly derided for busts in coverage in recent weeks, but produced a superb performance at the perfect time to help San Francisco into the conference championship.
Hufanga's two highlight reel plays were a pair of perfectly timed blitzes on which he burst into the Dallas backfield unblocked, with Dak Prescott somehow able to avoid a sack on both occasions.
Beyond those two pass rushes, however, Hufanga made a series of impressive plays in coverage as the Niners restricted the Cowboys' aerial attack.
Hufanga displayed excellent route recognition and understanding of his responsibilities to prevent Prescott from connecting with Dalton Schultz on a route bending over the middle of the field. The second-year safety was extremely quick to trigger on the route, but was disciplined enough to not make contact with Schultz too early.
While known for his aggressive playing style, Hufanga is a player who relies on film study and on his eyes to make the splash plays that have been a pre-eminent feature of his first full season as a starter.
Hufanga's eye discipline was crucial to this stop against the Cowboys, on which he threatened a blitz before reading the play-fake between Prescott and Ezekiel Elliott and subsequently dropping into coverage and then finishing the play by getting downhill to stop Schultz after Prescott checked the ball down to his tight end.
Also pivotal to that play was linebacker Dre Greenlaw, who was not fooled by the backfield action and demonstrated his proficiency in coverage by immediately understanding his assignment and turning his hips to take away wide receiver CeeDee Lamb on the over route over the middle.
Overshadowed somewhat by All-Pro linebacker Fred Warner's success in coverage against Lamb, Greenlaw was outstanding against the Cowboys, delivering a performance that would have been capped by a pick-six had he caught the ball after displaying excellent read-and-react ability on this short Prescott throw late in the fourth quarter.
The best example of the 49ers excelling on defense because of their personnel's prowess for diagnosing the game came on Fred Warner's red-zone interception. That pick was down predominantly to Jimmie Ward, who, understanding the wheel route to Schultz would be covered by Deommodore Lenoir with the Niners dropping to quarters, made no effort to follow the tight end into the flat and instead broke in front of the short throw to Lamb and tipped it into the grasp of Warner.
From Hufanga and Ward to Warner and Greenlaw, the 49ers were assignment sound for most of their narrow win over the Cowboys, combining their physical gifts with strong diagnostic skills to severely restrict Dallas' avenues to big plays.
The problem the 49ers face in the NFC championship game is that the Eagles have significantly more avenues to big plays. Theirs is arguably the most diverse run game in the NFL, with the additional running threat posed by quarterback Jalen Hurts allowing Philadelphia to place doubt in the minds of second-level defenders when attempting to read the mesh point.
Indeed, the dual threats of Hurts and Miles Sanders enable the Eagles to stretch defenses horizontally with their backfield action, with the extra hesitation the former can force among defenders opening the RPO game and the screen game for Philadelphia and creating a plethora of easy buttons for the quarterback.
The 49ers cannot allow themselves to be paralysed by that hesitation. However, they also cannot afford to consistently misdiagnose plays in the backfield against a Philadelphia offense that, in A.J. Brown, DeVonta Smith and Dallas Goedert, has the top-tier weapons to punish San Francisco downfield if the Niners' linebackers and safeties are caught out of position because of the complexity of the Philadelphia attack.
San Francisco reached this position in part because of the discipline of a defense that can match opposing offenses in its complexity. That discipline must not be allowed to slip for the 49ers to pull off the upset and book their place at Super Bowl LVII.
Story originally appeared on Niners Wire