Heisenberg's Uncertainty Principle is the quantitative bridge between de-broglie's equation and wave-particle duality.

let's not talk about football but an electron in a one-dimensional box.

assuming we can see the electron with our naked eye,

In a closed box, the wave-particle duality of the electron allows the electron to be everywhere in the box (given it's a wave). since the electron is now everywhere, the electron (as a particle) must be moving in the box.

Opening the box gives us the position of the electron. The electron is stationery at one position inside the box. However, as a wave (when the box is closed), the electron is moving. Therefore, we conclude that we are uncertain of the momentum of the electron.

In fact, absorption/emmission spectra agrees with the uncertainty principle. we never get sharp lines, but peaks in the spectra.