A dozen games into his T20I career, Jofra Archer is already England's most important bowler in the format by a stretch. England win twice as often as they lose with Archer in the side and can rely on him both to take wickets and stem the flow of runs: in their 3-2 defeat in India in March, he was both their leading wicket-taker and their most economical bowler - despite playing through an elbow injury and with a fragment of glass lodged in his hand.
While Archer's inclusion in the ODI side ahead of the 2019 World Cup brought much-needed quality at the death, it is in the powerplay that he is crucial to the T20I set-up. In 12 appearances to date, 23 of Archer's 47 overs in the format have been in the first six, and while he has only taken five new-ball wickets, his economy rate in the powerplay (7.08) has stopped teams getting off to fast starts and forced them to take more risks against other bowlers.
But Archer excepted, England have struggled with the new ball in T20Is over the last two years. They made significant improvements in India, opting to frontload by using Archer, Mark Wood and Adil Rashid in the first six overs, but were among the least effective sides in the phase in the world in the 18 months prior; out of full-member nations, only Ireland leaked more runs per over, and only South Africa took wickets less frequently.
So Archer's injury-enforced absence from their six T20Is this summer, three each against Sri Lanka and Pakistan, will provide England with a significant test of their short-form seam-bowling depth. It starts with back-to-back games on Wednesday and Thursday in Cardiff, one of the few grounds in the country where spinners have been more expensive than seamers in T20 in the Blast this season.
They are almost certain to pick Chris Jordan - who has played in 52 of England's last 53 T20Is - despite him leaking 10.51 runs an over in India and it would be a surprise to see either Wood or Sam Curran miss out, but there is room for one more seamer, with the recalled Chris Woakes and David Willey competing for a chance with the new ball ahead of the T20 World Cup in the autumn. A schedule including two games in the space of 24 hours and three in four days will undoubtedly lead to some rotation, too.
Curran has shown glimpses with the new white ball, but he played only a bit-part role in India, bowling an average of two overs per game and primarily in the middle overs, while Jordan generally bowls one in the powerplay, one in the middle and one at the death, and with middle-over 'enforcers' on the rise in T20, Wood seems best suited to that role. That means that whichever of Woakes and Willey plays could bowl as many as three powerplay overs, depending on how Morgan opts to use Rashid.
Willey's inclusion is particularly intriguing. He was England's player of the series when recalled for three ODIs against Ireland last year, but was an unused squad member against Pakistan later in the summer and left out entirely for the Australia series that followed. A stress fracture ruled him out over the winter but his return suggests he is a genuine option for the World Cup, swinging the new ball, providing variety with his left-arm angle, and adding batting depth from the lower order.
Woakes, meanwhile, has won a recall after six years in the T20I wilderness. It is an intriguing call to bring him back, given he did not bowl a ball in the format between August 2018 and the start of this year's IPL, and the decision may well be linked to his "wasted" winter on the sidelines while earning nearly seven figures a year thanks to his all-format central contract. Woakes has shown in ODI cricket that he is capable in the middle and death overs but the powerplay is his strongest phase by a distance, nipping the new ball around off the seam; this is an unexpected chance but it would be no great surprise to see him take it.
"Both Dave and Chris have played a lot for us in the past in both 50-over and T20 [cricket]," Eoin Morgan, England's limited-overs captain, said on Tuesday. "We know the potential that they have, and it's great that they're back involved specifically in the build into the World Cup.
"There's been a drastic improvement [with the new ball] - when we were in India, we did take wickets earlier than expected and it's probably been our marked improvement over the winter. Hopefully we can build on that and look at other areas of improvement alongside it."
England have further calls to make regarding death bowlers and the balance of their side. With Ben Stokes only returning from injury on Sunday and not part of this squad, Moeen Ali is likely to play as the second spinner and bat in the top six. Morgan explained that Liam Dawson's ability to bowl in the powerplay was a major factor in his inclusion as the third frontline spin option ahead of Matt Parkinson, and while Liam Livingstone could offer another option, Cardiff's short straight boundaries are usually unkind to spinners.
As for the death options, Wood and Jordan both leaked more than 12 runs an over in the final five in India, while Tom Curran struggled badly in South Africa at the end of last year. With Sri Lanka relatively light on finishers, not least after Thisara Perera's retirement, England will doubtless aim to take early wickets and be bowling at the tail by that stage of the innings - but without Archer to call upon, that is easier said that done.

Matt Roller is an assistant editor at ESPNcricinfo. @mroller98