"... even Fernando Diaz and Alejandra Alonso, two of Brazil’s finest, allowed the Quaffle to slip through their fingers twice apiece."
-- Ginny Weasley reporting for the Daily Prophet, 4 July 2014 (Pm)
Fernando Diaz was a Chaser for the Brazilian National Team at the 2014 Quidditch World Cup.
In spite of the efforts of the Haitian Keeper, they had a fairly easy win over the Haitian National Team for their first match of the tournament, the Chasers scoring 100 points before Haiti was disqualified for an illegal Snitch capture. The quarter-final against Wales was marred, in the end, by the violent behaviour of Gwenog Jones, the Welsh manager, who literally cursed the face off Brazil's manager, José Barboza, after a game where Diaz put in a "solid" performance (Pm).
During the two-day semi-final match against the United States, Diaz dropped the Quaffle twice, but the team eventually won by 420 points to 310. However, although Diaz and the other Chasers scored several fantastic goals, the team lost to Bulgaria, after a thrilling Snitch capture by veteran Seeker Viktor Krum (Pm).
Other canon notes and references
Fernando is the Portuguese and Spanish version of Ferdinand, originally Ferdinando, an old Spanish form of a Germanic Visigoth name, meaning fardi "journey" and nand "daring, brave" (Behind the Name).
Diaz is a relatively common Spanish surname meaning "son of Diego" (which itself may either be a shortened form of Santiago or come from the Latin Didacus (Greek διδαχη didache) meaning "teaching") (Behind the Name). The Portuguese equivalent - and hence more likely for a person from Brazil - is Dias.
As he comes from Brazil, Diaz may have attended the Castelobruxo Wizarding School.
From the Web
Screenshots of the Daily Prophet's coverage of the 2014 Quidditch World Cup: http://imgur.com/a/AXutv