Walker is of that age where you do start to worry. At the beginning of each season, you wonder to yourself, "Is this when his legs will start to go?"
He's just so critical for us in those high-level games, especially in the Champions League. Look at how badly we faded when he had to come off in the quarter and semi second legs last season. Atletico were cutting through us down that side, and should have forced extra time. Madrid only grew into the game after Walker limped off, and their first goal came from the right side.
He's also the only fullback in the world who genuinely strikes fear into Mbappe's heart. Mbappe took one glance at him last November and decided to switch sides, never even trying to run at Walker once.
We just need to squeeze a season or two more out of his legs. That's the most we can fairly expect of him.