Cape Town, February 5: Eoin Morgan acknowledged England were "way off the mark" after Quinton de Kock inspired South Africa to victory in the opening ODI at Newlands.
In England's first ODI since winning the World Cup, the tourists lost by seven wickets as new Proteas 50-over captain De Kock scored an imperious 107 to lead South Africa to victory.
England, without Ben Stokes and Jos Buttler, had looked set to amass a big score with openers Jason Roy and Jonny Bairstow ticking over neatly, only for the tourists to suffer a batting collapse similar to those which have plagued the Test side over the last year.
Joe Denly (87) and Chris Woakes stood firm to help England to 258-8, but De Kock and his South Africa side ultimately had too much - with Temba Bavuma (98) also weighing in with a hefty score.
"We were way off the mark and we were hurt," Morgan said at the post-match presentation.
"South Africa completely outplayed us today in all departments. We've got no excuses. We didn't adapt to the conditions today that were set in front of us, [because] we knew it wasn't going to be an absolute run-fest.
"But apart from Joe Denly and Chris Woakes we really struggled to get going, which probably emphasises that we are a little bit rusty.
"South Africa bowled well and accurately, they used the conditions really well with slower balls, and then we couldn't penetrate the partnership between de Kock and Bavuma, so it made things very difficult for us. But full credit to them, they've started the series very well.
"I think we lacked adaptation to the skill level that was needed. The guys up front came hard like they normally do, as we always try and do, but when that didn't come off we had to try and rein in in a little bit.
"I think we lost wickets in clusters, and when myself and Joe [Root] went at the same time, we continue to lose wickets until the Woakes and Denly partnership. But I suppose that total would only get us in the game if we bowled well and managed to take early wickets. but having let those guys get themselves in, it was a struggle to drag things back."
However, Morgan believes England, who gave ODI debuts to Tom Banton and Matt Parkinson, along with recalling Chris Jordan to the 50-over team for the first time in over three years, will have learned plenty from the chastening defeat.
"I think they learned a huge amount," said Morgan. "Failure is a huge platform to try and catapult yourself forward and learn from your mistakes. As soon as you can, (you have to) implement them into this series.
"I think the two guys making their debuts, Banton and Parkinson, have come in today and seen what international cricket is like. They've had a little glimpse of T20 international cricket but it's not all crash, bang, wallop, like we've seen today.
"So they learn a lot from tonight and hopefully take that into the rest of the series."