I think that's missing the point. What I said was people said "Depay/Martial were going to win Utd the league", not that "if we sign Depay/Martial....".
Regardless, they went to play under Van Gaal, who got a lot out of their academy and still he couldn't make use of the two. If we're going to tow the line of "Poch could have made that {insert flop here} good for us", where do you stop?
You could literally apply that to any player. He's not a magician though, and we've seen plenty that we've actually signed with high hopes, who leave with the door hitting their arse and Poch closing it.