Arsenal have made some great signings in recent years, but few will have yielded as much of a return in valuation as that of Gabriel Martinelli. The 22-year-old has been a real success story for the Gunners, whose scouting department will no doubt count him as one of their greatest finds. When Martinelli joined Arsenal back in 2019, he was a talented 18-year-old prospect arriving in north London from modest Brazilian outfit Ituano. In addition, the Gunners paid just £6million for him, making him a fairly inexpensive acquisition, but it also meant his signing flew underneath the radar somewhat….