Trevor Bayliss identified inexperience and faulty fielding as England's most pressing problems in their one-day international series defeat against South Africa.
England's coach agreed with captain Eoin Morgan that their young team must learn from experience after losing a 2-0 lead to end up with a 3-2 series defeat, after falling short in Sunday's decider at Newlands.
AB de Villiers' unbeaten 101, his 24th ODI hundred in his 200th match, cancelled out Alex Hales' 112 as England lost despite an individual century in a third successive match.
There was minimal support for Hales as the tourists were bowled out for 236 in 45 overs.
Then even after Reece Topley had taken three early wickets, De Villiers and Hashim Amla (59) eased South Africa into position to prevail with six overs to spare.
Bayliss conceded England did not come up with their best cricket when it mattered most.
"We've certainly got some work to do there, and that will come with experience," he said.
"At some point, that experience has got to pay dividends I hope playing against someone like De Villiers and the way he went about the innings today, is something we can learn from and that will rub off."
This is just the third time any team has hit back from 2-0 down to win a five-match series, and Bayliss believes his young team will become more consistent with maturity.
"I think to win series, we've got to take a leaf out of De Villiers' book, the way he paced his innings," he said.
"The best batter in the series did his job today, and showed everyone how to do it.
"I think the consistency of performance will come with experience, but sooner or later guys have to be accountable."
De Villiers was proud of South Africa's resilience, but had praise for England too.
He said of the opposition: "They're a fantastic one-day team.
"To come back from rock-bottom, in the 2015 World Cup, to where they are now ... the talent was always there, but mentally they had to go through a few obstacles.
"'Morgs' played a big role in that. He's a very positive leader and he's the right captain for England.
"They will be a team to deal with over the next few years. In the 2017 Champions Trophy, 2019 World Cup, they'll be around - there's no doubt about that."