"I had my goals and dates I wanted to be back, but my injury has healed quicker than I thought it would. It's enabled me to have this opportunity."
The knee, though not without some discomfort after heavy workloads, is now as solid as a rock.
"I don't think about it now. It's only when jokers like you ask me about it!"
He says there were no dark days about never making it back, not just from surgery, but to get back on the field and be able to perform at a high level.
"No, I always had a lot of belief to make it back. The surgeon said I possibly wouldn't get back to playing at international level."
On Saturday he will prove that prediction wrong. Also helpful was the odd chat with Silver Ferns netball defender Casey Kopua, another from Waikato, who underwent gruelling rehab on a bad knee injury, but has won her World Cup place. Kerr-Barlow knows he will have to keep on top of his rehab and stretching for the rest of his career.
For now, he is looking to repay the faith. If he does, then he may even swap with Brad Weber when the All Blacks consider their squad for the July 17 Rugby Championship opener.
"They will reassess me after the Fiji game. They don't want to chuck me in the pressure-cooker straight away.
"I didn't expect to be named at all, so I was stoked. Obviously, I was liaising with them throughout my injury. My goal was always to make that RWC squad. A lot of hard work has gone in and there's more to come."