His test career was blossoming, and Boult has repeatedly pointed out test cricket is his priority. That said, he was determined to be a part of the cup campaign. He is ranked sixth best bowler in the test game and a rising 15th in ODI cricket.
Boult would have been back last summer but for an untimely injury but his ability to swing the new ball has produced substantial problems for opposing batting lineups.
It's worth noting 19 of his 21 victims have been in the top seven batsmen for their teams. Not once in the World Cup has he failed to take a wicket; against Australia he was spectacular as he swept through their middle-lower order.
Boult grabbed five wickets at the cost of a solitary wide in the space of 17 deliveries to rout Australia for 151.
It wasn't enough to secure New Zealand a comfortable win on a madcap day at Eden Park, but he then survived two important deliveries from his Australian counterpart, Mitchell Starc - who was on a similarly devastating tear through New Zealand's innings - which enabled Kane Williamson to strike his match-winning six.
Boult's success has been based on swing. Late swing, where the ball deviates sharply just before reaching the batsmen, is among the most effective tools in a fast-medium bowler's armoury.
Confidence certainly helps, and Boult is an attacking bowler. Sitting back and attempting to contain would be a waste of his skills. His captain, Brendon McCullum, endorses a full-on attacking mentality, and has supported him with a phalanx of slips throughout the cup. At times he's been expensive but in the ODI game these days, where batsmen generally rule, that can happen.
Even so, taking 21 wickets at 15 runs apiece is testimony to his remarkable form on this wondrous ride through the last six weeks.
