Gareth Southgate hailed England's young guns as Phil Foden and Declan Rice scored their first international goals in a 4-0 demolition of 10-man Iceland on Wednesday.
Southgate's side were already out of contention to reach the Nations League finals after Sunday's defeat against Belgium.
But Southgate had insisted the dead rubber was important to his planning for next year's European Championship and his players took that message to heart.
Rice netted in the first half at Wembley as he became the first West Ham player to score for England in 10 years.
Chelsea midfielder Mason Mount increased England's lead before Foden struck twice after Iceland defender Birkir Mar Saevarsson was sent off for two bookable offences.
It was a sweet moment of redemption for Manchester City playmaker Foden, who had been sent home in disgrace along with Manchester United's Mason Greenwood after the pair broke coronavirus protocols during their trip to Iceland in September.
Foden, 20, is the youngest England player to score more than once in a single match at Wembley.
"I am really pleased for him. He is such an exciting player. It was a big week for him to come back in and, of course, not easy to walk through the door when you left how you did previously," Southgate.
"We knew what he is capable of. To get the two goals today was a glimpse for everyone of what he is capable of."
It has been a frustrating year for Southgate as England struggled to establish any momentum on the pitch, while there was a rash of unwanted headlines provoked by several of his players' off-field antics.
"We've got to learn from those experiences. We shot ourselves in the foot throughout this period. We made life difficult for ourselves off the pitch," Southgate said.
The England manager must be glad to see the back of 2020, but he will hope his team's last game of the year serves as the springboard for a successful European Championship campaign.
- 'Fabulous crop' -
Encouragingly, for the first time since 1883, England had three players aged 21 or younger score in the same match.
"For the last three days the mentality has been outstanding. With England there is always something to play for," Southgate said.
"There are big opportunities for young players, especially. We are trying to build and improve all the time. The hunger to play and the application pleased me.
"There was some lovely football. It was good to watch and for the young players to get the goals was very special for them.
"We are very conscious of the crop of young players coming through. We think they will be fabulous for England for years to come. It was great for the public to get a glimpse of that."
Southgate had been criticised for his cautious tactics of late.
But, inspired by Foden and another eye-catching display from Jack Grealish, this was a much more entertaining performance.
"There were excellent performances, especially for Jack Grealish. It's good balance to have an attacking-minded player in the position," Southgate said.
"The squad that we've had over the last three months is going to peak in the next three to five years. We'll invest the time in them."
England took the lead in the 20th minute when Foden's free-kick found Rice, who just beat the offside trap to glance his header into the far corner from six yards.
Aided by Iceland's shambolic defending, Mount doubled England's lead in the 25th minute, seizing on the loose ball from Bukayo Saka's cross to slot home from close range.
Saevarsson saw red in the 54th minute after tugging back Saka and England finished the job in ruthless fashion.
Taking Jadon Sancho's pass in stride, Foden guided a cool finish in the bottom corner in the 80th minute.
Foden rounded off the win five minutes later when he drilled home from 25 yards.