West Ham United have been scouting Rio Ave, a mid table Portuguese team, for a year. In February 2016, West Ham sent an official to watch the club, and their visits have been regular since.
It’s not reported who West Ham have been watching, and it’s not immediately clear. A process of elimination, removing players who have only recently joined, would leave a handful including 25 year old central defender Roderick Miranda and 21 year old attacking midfielder Filip Krovinović.
There’s every chance it’s neither of the above, but it would appear West Ham certainly have their eye on someone. Scouting Rio Ave continually isn’t like sending someone to watch Benfica, Sporting, Porto or Braga, where the talent is plenty.