"Just like we drew it up," McVay said.
The Rams snapped their six-game losing streak in spectacular fashion, led by Mayfield, who was playing two days after he was claimed off waivers. Mayfield came off the bench after Los Angeles' first series, replacing starting quarterback John Wolford.
After the Rams had trailed by 13 points in the fourth quarter, Mayfield led the team on a 98-yard game-winning drive, ending with a 23-yard touchdown pass to wide receiver Van Jefferson with 10 seconds remaining.
"I don't know if you can write it any better than that," Mayfield said. "Obviously we'd like to be a little bit more stress free, but it's a pretty damn good story, I'll be honest with you."
According to the Elias Sports Bureau, the 98-yard drive was the longest go-ahead touchdown drive that began in the final two minutes over the past 45 seasons.
"You can't say enough about Baker Mayfield and the leadership, the resilience [and] the competitiveness," McVay said. "And what a quick study. I mean, he just got here five minutes ago and figured out a way to be able to do some special things tonight."
Mayfield said the past three days were "pretty hectic," as he went from Carolina on Monday to playing in Los Angeles on Thursday night.
"Some tough decisions, but everything happens for a reason," Mayfield said. "Right now I've just got a lot of emotions, but I'm really, really blessed and I'm really thankful right now, especially just the guys here that welcomed me in and helped me do the crash course here."
After stopping Derek Carr and the Raiders at the 2-minute warning, the Rams found themselves in a precarious situation when AJ Cole dropped a 64-yard punt at the Rams 2. With no timeouts, Mayfield led the Rams downfield and got to the Raiders' 23 with 15 seconds left. Mayfield then connected with Jefferson in the back corner of the end zone.
On the winning play, Mayfield said he was "completely shocked" to see the Raiders line up in press coverage with 15 seconds left.
"I really thought they were going to pop out and play zone," he said. "But they just stayed with it, and I saw the weakside safety stay down, and Van's a great go-ball runner, go up and get it, and he won off the line and did a good job."
Mayfield completed 15 of 20 passes in the fourth quarter, the second-most completions in any quarter of his career, according to ESPN Stats & Information.
A former Heisman Trophy winner and No. 1 overall pick, Mayfield was asked where Thursday night's comeback win with his new team ranked among his career highlights.
"This is up there, to be honest with you," he said on the Amazon broadcast. "I didn't think it was going to play out like this, but I am sure happy we covered the two-minute operation, my goodness."
Mayfield is 0-22 in his career as a starter when trailing by 13 or more points, but this was the second time he has led a 13-point comeback off the bench. He also erased a 14-0 deficit in his NFL debut in 2018.
Despite starting the game, Wolford didn't attempt a pass. It is the third time in the past 10 seasons that a starting quarterback did not attempt a pass, according to ESPN Stats & Information.
Mayfield has now played for three teams in his first five seasons, making him just the second player taken No. 1 overall in the common draft era (since 1967) to do so.
Information from The Associated Press was used in this report.