It has been cricketing lore ever since an American called Bart King toured England in 1897 and started taking wickets with a delivery known as ‘the angler’.
As almost every bowler will tell you, when there are clouds in the sky and humidity in the air, the ball will swing. Weather conditions, it is nearly always said, play a huge part in one of cricket’s most complex and mysterious arts.
But is that right? When a captain or commentator says you must look up and not down at the pitch when deciding whether to bowl or bat upon winning the toss because cloud cover will dictate movement through the air, are they actually talking nonsense?
One man who believes they are is Nick Allum, emeritus professor of Research Methodology at the University of Essex and a club cricketer for more than 40 years.
Allum is convinced that swing bowling, or ‘swerve’ as it was known in the early 20th century after King pioneered it, has little or nothing to do with the weather and everything to do with the particular ball being used and the skill of the bowler.
“I got interested in this as a social scientist and keen cricketer as it always seemed quite outlandish to me that cloud cover and humidity could have such an effect on swing,” says Allum, who has spent years railing against this particular cricketing convention.
“So I wrote a piece in The Conversation (a website for articles authored by academics and researchers), asking why people would think swing was all about conditions. We just didn’t know whether that was true. All we had were anecdotes from players and pundits who always said, ‘Oh, when the clouds are there, it swings’.
Australia appeal for LBW against Ray Illingworth as Bob Massie takes 16 wickets on Test debut against England at Lord’s in 1972 (PA Images via Getty Images)
“Then I thought: ‘How can I prove they’re wrong?’. So, with the help of a proper statistician to make sure I didn’t do anything stupid, I got hold of 10 years’ data from Tests at Lord’s and looked at the degrees of swing.
“We had information about the ball itself and who the bowler was, what the wind velocity and direction were, and other things such as humidity. And, as I suspected, there wasn’t really anything going on with conditions to affect the amount of swing.
“Not surprisingly, the biggest influence was the ball itself because that’s the thing travelling through the air. Why wouldn’t it be the main factor?
“It was actually quite stunning to see the amount of variance you could explain just by looking at the ball. There could be a ball not swinging at all and then a different one in the same conditions was swinging loads.
“The conclusions in a nutshell were that the overwhelming factor in the amount of swing was the ball being used and how the bowler was using it. The wind made a little bit of difference, but only one or two per cent variance compared to 40 per cent with the ball. We thought this was exciting, but it didn’t go any further. Then I heard about Aaron’s work.”
Aaron is Aaron Briggs, who was so fascinated by the science of swing that he compiled a PhD at Cambridge University created and funded by English cricket’s governing body, the England and Wales Cricket Board (ECB), entitled ‘The aerodynamics of cricket ball swing’.
He takes up the story. “First, I looked at the bowler,” says Briggs, now a consultant for the ECB. “The speed they deliver the ball, the way they angle it when it comes out of the hand, and the rotation on it, the seam position — all those technical things.
“Then there’s the ball itself. You can have the same delivery by the same bowler, but if you change the ball, it’s going to impact how it moves through the air.
“The only way conditions will impact the way the ball swings is the block of air the ball travels through. That’s the only way the atmospherics can affect swing. People love one-to-one correlations like cloud equals swing, but actually, it is not the case at all.”
That may be the scientific conclusion of the experts, but bowlers are not so easily convinced.
Jason ‘Dizzy’ Gillespie was one of Australia’s great swing bowlers, taking 259 wickets in 71 Tests, and has gone on to be one of the game’s most respected coaches and now a pundit who will be commentating on the forthcoming Ashes for ABC.
“The bowler’s skill is the most important factor in swing: their release position, what the bowler’s arm path is, and getting wrist and fingers behind the ball,” Gillespie tells The Athletic. “Say a right-arm bowler wants to bowl out-swing, is the seam slightly angled?
“If they release the ball at a certain angle with their wrist and fingers pointed in a certain way, a flick of the wrist then gets that ball rotating backwards with the seam upright facing down the wicket. That gives them the best chance of getting swing.
“Yet, whether it’s the placebo effect or not, I don’t know, but bowlers do believe the ball is more likely to do something when it’s overcast. It might just be that they feel more confident if it’s cloudy, but in my experience, the ball has swung more when it’s been overcast.
Jason Gillespie was a fine swing bowler for Australia (Tom Shaw/Allsport)
“I’m no meteorologist or scientist, but I know, in all conditions, as a bowler, it’s a feel thing. You feel like there’s more chance of the ball moving off the straight if it’s overcast. It’s hard to put your finger on it, but you just feel it’s more conducive to swing when it’s muggy or the atmosphere is lower.
“Naturally, when it’s overcast, you’re probably looking to pitch the ball up a bit further, which gives it more chance to swing. If you identify early on a bright and sunny day that the ball isn’t swinging, maybe bowlers will tend to bring their length back a bit and hit the pitch harder. And if you do that, it’s going to give the ball less chance to swing.”
Gillespie’s last point rings true with Briggs. “When bowlers think conditions are in their favour, they are more likely to execute their skills and make it swing, hence creating a self-fulfilling prophecy,” he says.
Mike Selvey took 772 first-class wickets, mostly for Middlesex and almost entirely bowling swing, and played three Tests for England, dismissing Roy Fredericks, Viv Richards and Alvin Kallicharran in his first 20 balls on debut against the West Indies in 1976.
“The very best swing bowlers, people like Jimmy Anderson, have a very strong wrist action,” says Selvey, who, after retirement, became a highly respected cricket correspondent and commentator and latterly the president of Middlesex County Cricket Club. “But that only plays a minor part because everything you do is geared towards the ball coming out of the tip of your middle finger.
“You need to get purchase on the ball and get back-spin, which is really important. I used to try to get that by having sticky, tacky fingers.
Jimmy Anderson bowling in the nets at Lord’s in July 2024 (Gareth Copley/Getty Images)
“It’s like a golfer getting draw or fade. Imagine there’s an obstacle in the middle of the pitch. You have to force the ball around that obstacle and that mental picture is important. You have to work on it and get shine on one side of the ball and keep the other dry. But some days it goes and some days it doesn’t.
“There are definitely days when you can tell whether it will swing or not, and I think that’s atmospherics.
“Take Lord’s, for instance. The prevailing wind is westerly and that makes it swing. If it’s easterly, it isn’t going to swing. It must be something in the air. When it’s cloudy, there’s low pressure and the air is thinner. When it’s cloudless, the air pressure is high and it doesn’t seem to swing as much.
“I’d cite Headingley as a prime example. The cloud comes over and suddenly it’s moving through the air a lot more. That’s not the ball or the bowler. That’s the atmospherics.”
Gillespie and Selvey are almost certainly talking for professional bowlers worldwide, but the academics would like to see a more open attitude towards science.
“I went on the World at One (on BBC Radio Four) with Jonathan Agnew (the former Leicestershire and England bowler turned Test Match Special commentator and BBC cricket correspondent) to debate this when my piece in The Conversation was published,” says Allum.
“My main point was not that I knew anything specifically about the mechanics behind swing, but that we don’t actually know why it happens.
“The most interesting thing to me was that there wasn’t any actual evidence to support conditions affecting swing, just anecdotes, but Aggers rolled out the same anecdotes. He said: ‘I just know that when the clouds rolled in at Grace Road (when he played for Leicestershire), it swung’, and that was really annoying as a scientist.
“I’m not having a go at Aggers. It’s just that his views are typical. There was no engagement and that’s so common in the game. Players and pundits are so invested in the stories they tell for professional reasons, they find it hard to step outside that world.”
Mike Selvey (right) bowls David Gower for a duck at Lord’s in 1976 (PA Images via Getty Images)
Briggs concurs. “People say to me ‘you’re just over-complicating things’, but if you told someone who knew nothing about cricket that clouds affected swing bowling, they would say ‘it’s madness’,” he says.
“You hear people say ‘everyone says it, so it must be true’, but that’s the biggest confirmation bias I’ve ever heard. There is no real rigour for a scientific discussion within the game.
“In Major League Baseball in the United States, they had this whole Moneyball thing (the use of metrics to identify undervalued talent) where the data nerds won and they realised in-depth understanding can lead to success. That hasn’t really happened in cricket yet.”
And woe betide you if you tell Allum, an off-spin bowler with Chigwell CC in Essex, and Briggs, a wicketkeeper-batter with Sulhamstead and Ufton CC in Berkshire — “I can swing the ball and actually it’s quite easy to do at 50 miles per hour, but that doesn’t take any wickets,” he says — that they should look up rather than down should they win a toss.
“That shows you where the game is at,” says Allum. “We’re still based on anecdote and tradition rather than analysing what goes on. It’s just the way the game is. It doesn’t think about measuring it.”
“Look up not down is telling you to pay more attention to the weather conditions than the pitch,” adds Briggs. “Why make a decision on something so transient when you know the pitch is going to be a big factor in the outcome for five days?”
It is a valid point, but it does seem cricket is not listening to the ‘nerds’ when it comes to swing. Until the game does, those scientists who are seeking more emphasis on data will just have to carry on coming out swinging in the hope someone eventually pays heed.