"I wasn't in that conversation. But at the same time you don't want to miss out on being on the podium," the 31-year-old said.
Willis had hoped the pace would be put on from the bell, but instead it didn't come until down the back straight. He found himself unable to peg back the Kenyans and just pipped South African Johan Cronje for the bronze in 3:39.60.
Willis acknowledged he had not performed to his best at the London Olympics of 2012 and the last two world championships.
"I didn't want it to become a habit," he said. "If I didn't do it today I don't know how I would have coped emotionally going into Rio [Brazil, 2016 Olympics] where there is more pressure."
The mile event, where he will have another crack at John Walker's national record of 3:49.08s, is in Michigan at a meet for which he and wife Sierra act as directors.
"I missed Walker's record in Oslo [at the Bislett Games in June when he ran a personal best 3min 49.83s] so I'll see how I bounce back after flying back to the States.
"That'll be my last chance at the mile this year."
It may be small consolation right now, but Willis has been in impressive form recently, at a range of distances, including shaving 0.44s off his 1500m national record at the Monaco Diamond League meet.
It is easy to see why he was a frustrated runner on Saturday night. He knew the chance was beckoning and it didn't work out. Whether he would have caught the Kenyans is a moot point.
Still it is another medal and in time he'll likely come to appreciate that they all matter, albeit some more than others.
For the other New Zealander in the final, Nelson's Julian Matthews, it was simply a thrill to be in the race. He finished ninth in a time of 3:41.84.
"It was such a blur now, just running with those guys is huge for me," he said.
"I have raced quality guys but not so many so it was a good test for me."
