Is the top of the order still the best place to bat in the Hundred?

Ask any batter around the world where the best place to bat is in T20 cricket and they will give you the same answer: the top of the order. The field is up, with only two men outside the ring, and the new ball's hardness means that you get better value for your shots than at any other stage of the innings.

Yet something strange is happening. For years, openers have had the best records of any batting positions, leading the way in terms of both average and strike rate. But in the men's Hundred, openers are struggling. They are scoring more slowly than No. 3s, and averaging nearly 10% less than them. It invites the question: what is going on?

Openers themselves believe that the reason they are struggling is due to the ball. "The Hundred ball seems to be swinging a bit more than the T20 ball," Alex Hales said last week. "The ball is slightly different," explained Will Jacks. "We've found consistently that they swing more in the first few sets."

Phil Salt believes that some "indifferent" pitches have contributed. "It's been a theme in this competition," he said, after ending a lean run with 86 off 32 balls against Trent Rockets. "[Due to] a combination of the wickets and the balls doing more at the top of the innings, there are not many top-order batters in the most runs column."

Salt is right: heading into the final round of group games, his opening partner Jos Buttler is the Hundred's leading run-scorer, but only two of the top six - Jacks is the other - have opened the batting. Heinrich Klaasen, Colin Munro, Jordan Cox and Jamie Overton have predominantly batted in the second half of the innings, against an older ball.

For a sense of how difficult this season has been for openers, consider the quality of the eight batters who have opened at least three times and have averaged less than 20: Jason Roy, Devon Conway, Ben Duckett, Hales, Will Smeed, Zak Crawley, Jonny Bairstow and Dawid Malan.

What is so different about the ball? Players across the tournament have competing theories: some believe there is an extra layer of lacquer on it compared to the one used in the Blast, while others have suggested the seam is slightly narrower, or that the quarter-seam is stitched differently.

Kookaburra, the ball's manufacturer, told ESPNcricinfo that the specifications are "exactly the same" and that the only difference is the branding: the Hundred ball has a large 'H' logo imprinted on its side. But players are convinced there is a difference: Jacks wondered "whether it's the bit where it actually has the 'H' on the ball that makes it swing more."

Perhaps atmospheric conditions have also played a role: the majority of men's Hundred games are played under floodlights and much of the first two weeks of the competition were played under cloud cover and between rain showers. The weather has generally been cool, which is generally more conducive to lateral movement.

Either way, the ball-tracking data is unequivocal: according to CricViz, there has been more swing in the Powerplay in the Hundred this season than in any other T20 tournament on record in England and Wales. On average, the ball has swung 1.02 degrees in the first 25 balls of Hundred innings this season, compared to 0.81 degrees in televised Blast games.

And Powerplay averages have dipped significantly for seam bowlers. In the Blast, seamers collectively averaged 31.00 runs per wicket in the Powerplay, with a combined economy rate of 8.63; in the Hundred, those numbers have dropped to 25.14 and 8.46 respectively, according to ESPNcricinfo's data. Seamers are taking Powerplay wickets more regularly, and conceding fewer runs.

Of course, Powerplays in the Hundred and the Blast are not one and the same. In the Blast, they last 36 balls (30% of the innings), of which any given bowler can bowl up to 18 balls (50% of the Powerplay); by the end of the Powerplay, it is rare for the ball still to be swinging. In the Hundred, Powerplays last 25 balls (25% of the innings), of which any given bowler can bowl up to 20 balls (80%).

That means there is a more prominent role for specialist new-ball bowlers. Take Dan Worrall. Surrey's depth meant that he was only used once in the Blast this year but he has been a revelation for London Spirit, bowling 86% of his balls in the Powerplay. He has taken nine Powerplay wickets, the most of any bowler, and on Sunday night became the first man to bowl 20 of the first 25 balls in a Hundred game.

The movement on offer with the new ball has pushed captains away from the once-popular trend of bowling spin in the Powerplay. In the Blast, 17% of balls in the Powerplay were bowled by spinners; in the Hundred, that figure is just below 10%. Seamers are getting on top, and staying there - and with a higher concentration of talent, there is no let-up.

Batters can also get stuck on strike more easily in the Hundred, since end changes take place less frequently - every 10 balls, as opposed to every six - than in T20s. If a bowler gets on top of a batter, there is no respite: Salt and Crawley have both been dismissed for 2 off 11 this season after finding themselves unable to get off strike.

So whether it is down to the ball, the weather, the format or random variation, one thing seems clear: in the Hundred, the top of the order is no longer the best place to bat.