World record-holder Armand Duplantis made a smooth if unspectacular start to his outdoor season on Friday, winning the men’s pole vault at the Eugene Diamond League with a vault of 5.91m. The US-born Swede — known as “Mondo” — had victory in hand when he made three failed attempts at 6.07 and said that left a sour taste in his mouth. “I feel like when I go into any competition I want to get over six meters now,” said Duplantis, who set two world records in two weeks at the World Indoor Championships in March, taking the new benchmark to 6.20m. He won at the Diamond League in Doha earlier this …