As I said in an earlier post, you can't compare Traore and Costa this season, it's not fair. Traore played more than 9 games than Helder did in terms of minutes. Traore was also the focal point of all Boro attacks, he was literally their only outlet a lot of the time. In that time he was involved in 15 goals (5 goals, 10 assists) and Costa 11 (5 goals, 6 assists). Cavaleiro played close to the same amount of minutes as Traore and was involved in 21 goals (9 goals, 12 assists) which is a lot better and he was at no point the focal point of our attacks.
Look at Costa from 16/17 where he was our only outlet in a much weaker team than the one Boro had and Costa is involved in 18 (10 goals, 8 assists).
Traore's record is pretty much the same as Pablo Hernandez's (7 goals, 8 assists) and Jozefzoon's (7 goals, 7 assists) in about the same minutes but I can't imagine many people would fancy them - it seems to me that the appeal from Traore is just his pace. He's not better than our current 3 wingers as is, so by the look of it we are signing him as fourth choice. If the intention really is just to bring him on late in the game purely because he is fast we might as well just go put in a bid for Jefferson Montero, you can get him for less than a tenth of the price of Traore.
I'm being tongue-in-cheek when I say we should sign pacey Jeff, but if we are comparing similar players who were also in a team that barely attacks and can't score...
Traore 16/17: 16 (11) - 1537 mins. 0 goals, 1 assists.
Montero 15/16: 14 (9) - 1360 mins. 0 goals, 2 assists.
Montero 14/15: 15 (15) - 1570 mins. 1 goal, 7 assists.