Simply because of the surname, Armstrong. You can read a bit about Matthew Armstrong on his page at the Scottish FA, and see more cards of him. But what would almost certainly have been a great career was interrupted by the First World War, as were so many future stars of the time.
We know these cards were issued with “Prize Crop” brand because it says so on the special album in an odd shaped box which is most unaesthetically right on the front cover. “Prize Crop” was a brand of tobacco and cigarettes that was also sold in Australia and New Zealand, and a lot of its advertising featured sturdy young men in wide brimmed hats.