Though Goff led Los Angeles to a Super Bowl in 2018, he regressed, throwing 29 interceptions in the next two seasons.

Enter Stafford, who had played in and lost the only three postseason games he played in with the Detroit Lions despite throwing for 45,109 career yards, fifth among active passers entering this season.

McVay convinced General Manager Les Snead to trade for Stafford in a blockbuster exchange that included Goff and two future first-round draft picks, the team going all-in on building a championship-caliber roster ahead of this season’s Super Bowl, which the Rams will host.

The early returns on Stafford’s trade and the star acquisitions that followed — linebacker Von Miller and receiver Odell Beckham Jr. joined midseason — have been positive. The Rams won 12 games, claimed the N.F.C. West, and Stafford threw for 4,886 yards and 41 touchdowns. But his 17 interceptions were tied for the league-lead, and often doomed his team against quality competition.

That was not the case Monday night.

In the first quarter, instead of force-feeding Cooper Kupp, who was double teamed in the end zone, he smartly found Odell Beckham, Jr. in single coverage, who made an acrobatic leaping catch for a four-yard score.

He placed passes accurately for his receivers, who created separation and yards after the catch all night from the Cardinals’ defensive backs. Beckham Jr., who also faces his own postseason reckoning, caught the first playoff touchdown of his 8-year career and, for style points, laced a 40-yard pass to Cam Akers on a third-quarter touchdown drive.

With such a definitive victory under his and the Rams’ belts, Stafford may well see more career-defining games in the weeks to come.