Klaus wrote:
Because it's much easier to shoot over the goal than under it, like Henrik Larsson once said.
Pretty much - every single professional player has the technique to put it in the top corner 99% of the time. Nerves do funny things to you, and it's much better to go with a technique your familiar with than chopping and changing every week.
That said, Auba's pens are still far too high risk and basic rely on the keeper blinking first. De Gea lost his nerve, Lloris didn't and that was the difference