Hmm, so its a Premier League footballer that has drawn a cup game at home, thus has had to play the replay away. Given the fact that the post typically comes in the late morning, there must have been a fair distance to travel. Which should allow me to narrow down the options.
It seems likely to be a Liverpool player, given they had to travel down to Plymouth. And lets say its also likely to be someone less au fait with the postal system. Which leaves me with only one option. Alberto Moreno
Edit: Oh FFS. I had it all worked out, and while I was showing off my detective work the answer went and got posted.