The story was backed up by the Guardian among others, with the 27-year-old now almost certainly looking Baggies-bound - much to the discontent of fans of his ex-club.
In Sako, West Brom will be getting one of the best players in the Championship last season.
But is the former Wolves star better than another Championship winger West Brom were after earlier this summer: Michail Antonio?
Indeed, according to the Express and Star, Nottingham Forest rejected a bid for Antonio this month, while Forest boss Dougie Freedman's recent comments allude to an offer that was turned down.
|(Per Game)||Goals||Assists||Chances Created||Dribbles||Crosses||Final-Third Passes||Minutes Played|
As Opta stats show, Sako and Antonio produced similar figures in the league last season.
The ex-Wolves winger, however, averaged more goals per game and created more chances per match. Antonio edges Sako in terms of assists but that statistic is also dependent on his Nottingham Forest team-mates finishing his chances off.
In terms of dribbles, Sako won more per game and landed more crosses during his on-field minutes. In the final third overall, meanwhile, the 27-year-old completed more passes in the Championship.
While there are no doubt more areas to consider, then, former Wolves man Sako edges Forest's Antonio in terms of the stats and the fact he is a free agent. A good deal for West Brom?