A week ago at the Sir Vivian Richards Stadium, Jasprit Bumrah was bowling from an end of the ground where the breeze was blowing from right to left as he ran in.
So he thought to himself, "I'll bowl outswingers today."
On Saturday at Sabina Park, the inswinger was his stock ball. Perhaps the wind was blowing the other way.
It's remarkable that a fast bowler can simply turn up and decide to swing the ball one way or another. Bhuvneshwar Kumar can swing the ball both ways, and James Anderson learned to do it too, many years into his Test career. But they are swing bowlers, not genuine quicks operating around the magic 90mph mark.
If you can swing the new ball one way at pace, you already have the tools for a highly productive career - just ask Dale Steyn, or Shane Bond, or Ray Lindwall if you want to go back that far. To swing it at pace, and swing it both ways? Outside of Wasim Akram on his day, it is the stuff of schoolboy fantasies.
Bumrah is living a schoolboy fantasy right now.
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In Antigua, the outswingers brought him five second-innings wickets, for the cost of seven runs, in eight overs.
In Jamaica, the inswingers brought him five first-innings wickets, including a hat-trick, for the cost of 12 runs, before a bout of cramps forced him off the field after 6.1 overs. Then he came back and ended the day with a spell of 3-2-4-1.
In all, that's 11 wickets for 23 runs in 103 balls. Work out the average and strike rate yourself. Be amazed.
A shriek rang out from the slips cordon on Saturday after Bumrah had forced John Campbell to edge one behind with a deadly cocktail of line, length, late movement and steep bounce. The stump mic caught it clearly. Excitement had raised the voice to a higher pitch, but it was still unmistakably Virat Kohli. "What a bowler, man! What a bowler!"
Bumrah simply smiled that familiar smile of his; shy, almost polite. He doesn't do overt excitement.
It was entirely in tune with Bumrah's personality, therefore, when he was the only India player not to leap up in appeal when he struck Roston Chase on the front pad with a full inswinger, when he was on a hat-trick.
Imagine that. You're on a hat-trick. You hit the batsman's pad. You don't appeal.
Bumrah thought there was an inside edge. Umpire Paul Reiffel probably thought so too, or maybe thought the ball would have swung past leg stump.
From second slip, Kohli voiced his thoughts loudly. There was no bat onto pad, and the ball was hitting the stumps. Ball-tracking vindicated him, and Bumrah, watching Reiffel change his decision, managed a small hop, with that polite smile on his face, before his team-mates enveloped him in a collective embrace.
Even to them, Bumrah must be a marvel. He seems to add a new layer to his bowling with every match he plays. He can hit the deck and test batsmen with bounce. He can jag the ball both ways off the seam. He can pitch it up and swing it both ways. He can do all this at high pace, from over and round the wicket, and when you least expect it he can flummox you with a dipping slower yorker.
He is only playing his 12th Test match. He already has 60 wickets at an average (18.86) and strike rate (43.0) straight out of the late 19th century. He's taken at least one five-wicket haul in each of the four countries he's played Test cricket in. He's only 25.
Jasprit Bumrah doesn't do overt excitement, but if you're an India fan, or a cricket fan of any description, you should be very, very excited.