But the considered view of her lifelong coach - and one which is today endorsed by rugby legend Wilkinson himself.
"Think Beckham against Greece," said Toni Minichiello, Ennis' coach. "Last kick, goal needed for England to qualify for World Cup. Bang, thank you very much.
"Think Wilkinson against Australia in 2003. One chance to win the Rugby World Cup final. Right... okay... bang.
"There are only a handful of sports people who can rise to a challenge at times of extreme pressure. Who say to themselves, 'right, I need to do something here'. And they do. Jessica is one of those.
"Like Beckham and Wilkinson, Jess has that ability to say 'alright, let's go' and crank it up to beyond the capacity of others. Whether it's nature or nurture I really don't know."
Wilkinson recognises it as a desire which borders on an almost supernatural calling - and says he detected it in Ennis the first time they met.
"It was the first thing I picked up on," smiled English rugby's favourite son. "A sense that with her, as with me, it's not just sport. It's more.
"There's a choice involved because it's something you love doing and something you know you live to do. But there's also no choice in that it's too important."
That, according to Wilkinson, is what lifts certain individuals to the level that makes them able to perform when the pressure goes "crazy".
"The one thing that helps you go crazy with it, and rise to that level, is the fact it means that much," he reiterated.
"It isn't about waking up as a different person and trying to go through a process of converting yourself into a person capable of dealing with that situation.
"You wake up and you're already at the same level as the pressure, if not more, because it's too important - something greater than just a choice to play sport.
"It means everything to you. It's been in your blood for as long as you can remember. It's part of your being."
Ennis, enjoying the calm before the storm in Team GB's Algarve holding camp, knows this to be true and Minichiello does too.
He describes her as "incredibly competitive" and illustrates what he means with a story of when she was struggling with a javelin session and wanted to call it a day.
Her coach Mick Hill agreed, providing she first threw one further than she had all day. "Jess looked at him, said 'right then', and immediately did," laughed Minichiello.
"That's Jess. The toughest competitor I know."