You can define it by what the ball isn't. It's not a huge swinger; nor a yorker, and perhaps most importantly it isn't right-arm seam. The delivery is a half-volley that straightens, which is something any international batsman should be able to handle. And the batsman is not a regular player, but Joe Root. Earlier in the tournament, it was Kusal Perera, so the batsman is irrelevant, it's the bowler that matters.
The ball isn't straightforward; it's a 90-miles-an-hour ball, and while it is a half-volley, it is a fast swinging Mitchell Starc half-volley. Starc is so extraordinary; his half-volleys are as dangerous as other bowlers' yorkers. How do you play someone who's weaponised benign deliveries?
Mitchell Starc might be the greatest white-ball bowler there has ever been. And if he isn't the greatest, he's perhaps the most destructive. At the least, he deserves to be in any conversation.
Mitchell Starc has only played 82 ODIs, but in those, he has taken 162 wickets. That's basically two wickets a game. Bowlers don't take two wickets a game in ODI cricket. Starc takes a wicket every 25.4 balls. Waqar Younis took a wicket every 30 balls, Glenn McGrath 34, with Joel Garner and Wasim Akram 36. According to cricket analyst Mainuddin Ahmad Jonas' runs-above-average metric, Starc is equal-second on the all-time ODI bowlers list for with over 100 wickets. Jonas has him as 28% better than the average bowler during his career.
Starc averages 12 less than other bowlers who've played in his era and takes wickets off 13 fewer balls than the rest. Of ODI bowlers with over 150 wickets, no-one has a bigger differential for either.
There has never been a fast bowler like Starc in limited-overs cricket. He is not an ODI bowler; he's an ODI weapon.
At Trent Bridge earlier this month, Australia's top order collapsed to ensure they were several runs short of a par score against West Indies. And it was a deep and powerful West Indian line-up they were up against. Starc's first challenge was to deal with Chris Gayle. In one over he almost had him caught twice, and also had two on-field wickets overturned by DRS while also hitting the stumps without the bails coming off. One over later, he finally got his man.
Starc bowled two more spells in the game; each one came when Australia had just slipped behind. The first led to the removal of Andre Russell, and he did it by bringing up his straight fielders and following the batsman's body. There was no way Russell would wear the over. He played a pull shot while ducking, deflected one off the body for a couple and smashed one across the turf. But Starc kept going at him, and Starc won.
Watch on Hotstar (India only): All the wickets in England's run-chase
Starc came off, and the West Indies came back. With 30 balls left they needed 40 runs, so back he came with Carlos Brathwaite and Jason Holder in his sights. He finished with five wickets, and Australia finished with a 15-run win. It was a perfect example of Australia's gameplan in this World Cup. They muddle around for a bit, and then Starc the life out of their opposition.
Overs 30 to 40 never used to be important. They were the end of the "Boring Middle Overs", with perhaps - if wickets were in hand - a slight ramp up towards the death. But with the fielding changes meaning that four men out ends at the fortieth over, teams often attack between 30 and 40, because there are gaps in the field during that period that will be closed off in the closing overs.
It means that instead of your spinner or part-timers hurrying through their overs, you often turn to your best option. This is when Starc shows how important he is. With the new ball over the last few years, he's been average, and often worse. With these ageing white balls, all seamers in the world have averaged 32 in this period with an economy of 5.6 between the last two World Cups. Starc averages 15 in this period while going at 4.6 an over.
In this tournament, he's bowled 60 balls between the 35 and 40th over, and taken six wickets at an average of 10.66. Pat Cummins and Mehidy Hasan have delivered 100 deliveries between them for three wickets. The average for all bowlers is 33 in this tournament. He's bowled 117 balls that batsmen haven't been in control of, a remarkable 30% of his deliveries.
Just as set batsmen are about to go, Starc removes them.
Against Pakistan, Wahab Riaz was the dangerman, as Australia started to look like losing a game that shouldn't have been close. Starc bowled a quick ball from around the wicket, and Wahab edged a steepler behind. Goodnight, Pakistan.
At The Oval last week, Kusal Perera started Sri Lanka's innings as if he was planning on burning Australia's house down. He even feasted on some of Starc new-ball bowling. But back he came for a second spell, earlier than intended, and Kusal's stumps were the real victim. Sri Lanka crawled to a loss from that moment on.
Bangladesh started well against Australia with the bat at Trent Bridge, but Marcus Stoinis got rid of their Avenger Shakib Al Hasan for his only non-fifty of the tournament, and only Tamim Iqbal remained as a credible threat. When Tamim had reached his half-century, Starc came back and blew straight through him. Bangladesh were playing for net run rate from then on.
Australia might still have won some of these games without Starc, but instead they won all of these games because of him. Australian batsmen have struggled at times, the supporting bowlers haven't always been up to scratch, and some teams have pushed them. The answer every time has been to throw the ball to Starc.
A standard ODI seamer usually starts with Test lines and lengths, trying to nick the ball off an indecisive shot in the corridor. Then they come back for the middle overs, bowling cross-seamers and slower balls, looking for a mental error from the batsman. Before the death, they'll bowl with mid-on and -off up, and go short, protecting the square boundaries and hoping for a catch. The death will be about mixing it up, wide and straight, full and short, fast and slow.
Starc doesn't even really bowl standard line and lengths in Tests. The line seems unimportant to him, and he rotates between very full, very short, and somewhere in the middle. There is probably no successful ODI bowler of the modern era who tries slower balls less. Whether mid-on or -off are up - which they usually are - doesn't matter to him, he will bowl full regardless, backing himself over any batsman to hit him straight. At the death, for a bowler with what can often resemble a Jackson Pollock pitch map, he's entirely predictable: he'll go full and wide, or full and straight.
This entire tournament has had seamers banging in short balls with their higher likelihood of wickets, Starc - despite an ugly 90mph bouncer up his sleeve - has taken 15 of his 18 wickets with full balls. He's not playing the same game as the rest of you guys.
Starc refers to this as "a simple method". It's simple if you're a massive left-armer who hurls 90-miles-plus. The reason he can use a simple method is that he's not like a typical bowler. Much like Lasith Malinga, if you tried to bowl like Starc, it wouldn't work. Since the last World Cup, no seamer in the world has bowled more full balls than Starc after the 30th over, because the rules for them are different, and the balls would disappear.
When Starc bowls a length ball at the death, he can get away with it because he gets bounce. His length balls in the last 20 overs of the innings go at less than a run a ball, and he averages 10 from them. Everyone else is above a run a ball and averaging 20.
There are basic rules to ODI bowling, and there is what Starc does.
There has been only one game this tournament where Starc has struggled. Against India he went for 71 runs, and while he took the wicket of Shikhar Dhawan, it was late and after he'd scored a century.
Without Starc's wickets, the Australian attack looked ordinary, India couldn't be shaken, and they made a total beyond the reach of the Australian batsman. Starc's impact allows Australia to gamble on their fifth bowler. If Starc comes on and takes a wicket anytime from overs 10-40, Marcus Stoinis and Glenn Maxwell can burgle some overs. With the fear of Starc, it means teams might be more reckless to score from Australia's weaker third and fourth bowlers. If Starc takes wickets from 35 to 40, Stoinis as the death bowler is not as big a problem. If Starc is in this attack, it is not ordinary.
Watch on Hotstar (India only): Ben Stokes battles before Starc bombshell
Against India, Starc not only didn't strike when he came back at the death, but India could also swing at him with no fear. They scored 40 runs off his last three overs, but the other bowlers struggled more. Starc's only poor game is Australia's only loss.
The bails are on the ground and flashing, Ben Stokes' bat is next to them, and Stokes swings a boot at it.
The over before Starc's return, he was carving 90mph deliveries to the boundary. Cummins delivered the 36th. It was fast - not only due to the speed of Cummins but also in the velocity of the balls which Stokes slammed into the short offside boundary. First he charged and slashed through point, then he charged and hit through cover. The cover sweeper was stuck in the middle twice. When Chris Woakes hacked one through mid-on to finish the over, Cummins had leaked 13 runs.
England now needed eight runs an over with five wickets in hand and their very long batting line-up to follow. Australia were still favourites, but with Stokes set, Cummins looking shaky, and Woakes batting well, England had their best chance since the second ball of the innings.
There was no chance of the next over not being bowled by Starc. England were playing well, and these were Starc's special overs. Like Pavlov's dog, once the 35th over ticks over, he starts salivating over wickets.
The first five balls included a couple of singles and some slices through the off-side. Stokes was on strike for the last ball of the over. The ball was full and fast. It reversed, and before anyone had time to make a sandpaper joke, it hit the base of Stokes' off stump. It yorked Ben Stokes, it yorked the stumps, and Stokes fell over as he lost control of his bat. The delivery made you feel ill, it was so perfect, as if Wasim Akram and Joel Garner's yorkers had fallen in love and had a baby.
It didn't look real, it was computer-generated carnage. How do you play someone who's weaponised the old ball like this?
Stokes was on 89, he'd pulled England back from the brink, he'd slapped Cummins into submission, and now he was kicking his bat. There was nothing else left to do.
You can define the Starc yorker by what the ball is. Unplayable.
With stats input from Shiva Jayaraman