The long-standing debates over England's best batting line-up in T20 international cricket will roll on and on until October's World Cup but this 3-0 thrashing of an abject Sri Lanka side has been a reminder of the oddity of the tournament itself.

The draw for the World Cup - initially scheduled for Australia last year, but since shifted to India and now the UAE and Oman - took place 18 months ago, and in the intervening period it has become apparent that England have done well out of it: they have avoided West Indies and New Zealand, both of whom will be significantly stronger than their ICC ranking implies, and will see themselves as favourites against both South Africa and Afghanistan.

The result is that even if they are beaten heavily by India in the group stage, they need only beat those two teams, plus the two qualifiers from the preliminary phase, and they will reach the semi-finals, and be two wins away from their long-standing ambition of becoming the first men's team to hold both World Cups simultaneously.

This series proved that, while there are decisions to be made about the side's best combination and structure, the most important thing for England is that they have a deep, versatile batting line-up which is filled with players that can single-handedly win a game on their day. For Saturday's thrashing at the Ageas Bowl, they were without three of their first-choice top six - Jos Buttler (calf), Jason Roy (hamstring), Ben Stokes (returning from a hand injury) - while their first-choice No. 3 and No. 4 opened the batting and their back-up finisher came in straight after, yet their win was still a procession.

England's collapse from 143 for 1 after 15 overs to an eventual total of 180 for 6 looked for a fleeting moment like it might cost them after Danushka Gunathilaka punched the first ball of the chase through cover; as it turned out, it would have taken a declaration with five overs left to turn this into a competitive game, as Sri Lanka's batters collapsed in a heap. This was the sort of clinical performance that should help them annihilate the weakest teams in their World Cup group; unless they come unstuck in two of the other three games, they will cruise through to the semis.

Only then will their answers to the important questions come under real scrutiny. Where should Jonny Bairstow bat? How can they get more out of Stokes? Should Mark Wood bowl mainly in the Powerplay, at the death, or a bit of both? And the randomness of certain events - in particular the importance of the toss in floodlit games in the UAE, bearing dew in mind - could render such discussions useless anyway.

And so to Dawid Malan. Countless column inches have been filled, including on this website, by debates over Malan's value to England's side: nobody has ever started their T20I career with such compelling numbers and he has ensconced himself at No. 1 in the ICC's player rankings, but with such a strong set of batting options available to them, his slow-starting method and his occasional struggles on slower pitches, such as the ones expected in the UAE in October, has come under intense - and perhaps unfair - scrutiny.

This series has encapsulated the debate: his two low scores on two-paced Cardiff pitches were wholly unconvincing, but his dominant innings of 76 off 48 balls on a better pitch at the Ageas Bowl was one of high class: the other 72 balls in the innings brought only 92 runs off the bat. Even if his form "only has one way to go", as Eoin Morgan put it at the toss, his rate of success in T20I cricket has been phenomenal.

On Saturday, Malan managed what no other England batter has in this series by getting after Wanindu Hasaranga, Sri Lanka's blond-haired, bright-booted rockstar of a legspinner. Realising that ball spinning into his arc towards the shorter boundary represented a favourable match-up for him, Malan treated Hasaranga with disdain, thumping him for two fours and three sixes and scoring 34 off the 10 balls he faced from him; Roy was the only other man to hit him for four across the whole series.

The slog-swept sixes were brutal, but there was a touch of class, too: on 18 off 15, he reverse-swept him into the gap between short third and backward point, and in the same over nailed him over deep backward square leg and lofted him inside-out through the gap in the covers that his reverse-sweep had created.

"When you do your match-ups and look at the dimensions of the ground, with a right-hander in [at the other end], my match-up is to take down the legspinner towards that shorter boundary," Malan explained afterwards. "Even though it was into the wind, that was my role: to take the positive option against him.

"If that was an offspinner on that side, Jonny would probably have been over-aggressive against him because that was his match-up. I faced him the other night at Cardiff and didn't see him that well, and my movements weren't very good, so it was nice to face him a couple of days later in different conditions and get on top of him."

During his difficult series in India, it seemed as though the drawbacks of Malan's method outweighed the benefits, but in this innings, the opposite was true. He may not mind the debate rolling on: "I quite like proving a point so when I do get criticism I do like going out there to show those people that seem to have their opinions," he said.

There are similar questions to weigh up in the bowling attack: are Chris Woakes and David Willey viable options as new-ball specialists? Is Chris Jordan still a banker at the death? The absence of much new information from this series means they will not be answered definitively until the knockout stages of the T20 World Cup - and even then, there is another one to follow only 12 months later.

Matt Roller is an assistant editor at ESPNcricinfo. @mroller98