"Deal agreed", anything can be agreed anytime (wasn't Buonanotte signed outside the window?), but the transfer can only go through once the window opens.
It also goes a bit deeper than that, the group that own Right To Dream have set up a really clever system to funnel talent from Africa to Europe via a number of clubs around the world. It's worth a read on Wikipedia. I believe this will be the future of football, not that I support it.
They don't have access to our statistics. This is the key. Even if they had all the raw data I doubt they'd know how to interpret it. Until the time teams like Chelsea, Manchester City etc spend millions per year hiring dedicated analytics teams of 10-15 data scientists, we're always going to...