Why are some football shin pads so small?

Liverpool 's Lewis Koumas made his full Premier League debut against Manchester City on Sunday. While doing so, he sported some very low socks over what appeared to be a very small shin pad. Last season, images of Burnley's Marcus Edwards went viral after the 27-year-old was seen wearing barely visible shin pads during a Premier League match against West Ham. Two years ago, a picture of teenager Harry Howell celebrating with James Milner while they were Brighton team-mates also gained attention after fans noticed the visible difference in the size of their shin pads.