"He's been out of competitive cricket for a couple of years," McCullum said. "I think it's taken just a little bit of time to get that rhythm of gameplay back but I think he's been really good. He's bowled high pace, he's played a lot of cricket, he's been able to get significant workload under his belt throughout this time and we've seen moments of how great Jofra is, even tonight, a couple of wickets he took the other night against Afghanistan, three with the new ball.

"We know how great a player Jofra is at the very top of his game and to have him back and to have him fit and excited about playing is a real win for English cricket."

With one English eye perpetually on the Ashes, his ability to tolerate increased workloads is bound to raise hopes he can feature prominently in the five-match series at the end of this year. McCullum looked to balance hope with guarded optimism.

"We've got to make sure that we're always doing the right thing by Jof as well and understand the risks involved," McCullum said. "But I'm pretty sure he's pretty keen to play Test cricket and you look at someone like Jof - and if you can add him to the battery of fast bowlers you're trying to build, that can only strengthen this squad. We'll wait and see, but overall, I'm really pleased with where Jof's at and it's great to see him back playing and injury free at the moment."

That, however, is where the positives end. It has been little short of a horror start to his all white-ball stint for McCullum, winning three and losing eleven games, including the last seven on the bounce: England's longest such streak in ODI cricket since 2001. While McCullum said on Thursday England may quite plausibly have won each of their first two games, the crushing loss at South Africa's hands has left little doubt about the true state of their current ODI side.

"We weren't good enough across, obviously very disappointed," McCullum said. "We had high hopes of being able to finish the tournament with a bit of a bang, but we were very poor and we've got a lot of work to do. We'll put our thinking caps on over the next few weeks and start to try and navigate our way through what an improvement looks like across our white-ball cricket and make sure we try and be pretty thorough with that and work out a way that we can get ourselves back to where we should be."

His final innings as captain was a pale shadow of the player who will likely go down as the greatest white-ball batters in England's history. It ended when he tentatively pushed a Lungi Ngidi delivery straight to mid-off; he had scored 21 in 43 deliveries without hitting a single boundary - his second-longest such innings without sending a ball to the fence.

McCullum reiterated his plans to keep Buttler around England's white-ball side. "We still see Jos as obviously a big player within that and he's got a huge role to play. He cared so much about it and he admittedly said that he wasn't able to get the best out of the guys at this stage. I thought it was a brave decision to make and it gives us now an opportunity to be able to start to plot and plan our way forward.