Indeed. Case in point - Bas Dost. Look at his scoring records and you'd think he's one of the greatest strikers of all time.
Look at it deeper and he did the business in Holland, but when he got his move to Germany he was pretty average, and has kicked on again now he has dropped to a sub-standard league in Portugal. He'd very probably have done absolutely nothing in England.
Anyway, in regards to Kean, it still seems a weird transfer to me. I can't see it happening - I think it's a punt of a query from Brands and I expect him to stay at Juve, but we'll see. Either way, at 19, expecting such a transfer to be our definitive first team solution is... odd. Unless Brands/Silva see DCL as progressing well enough to rotate the two prospects.