"US Chaser Quentin Kowalski drew plaudits from all commentators for his deft weaving and rolling...."
-- match report USA v Liechtenstein, Daily Prophet, 8 June 2014 (Pm)
The USA also won against Liechtenstein by 450 points to 290, where Kowalski was singled out for praise. They then lost a two-day long match against Brazil, which put them into the playoffs for third place (Pm).
Other canon notes and references
Quentin is the French form of the Roman name Quintinus or Quintus, meaning meaning "fifth" in Latin, traditionally given to the fifth child or a child born in the fifth month (Behind the Name).
The second most common surname in Poland, Kowalski comes from the pre 7th-century word kowac "to forge" combined with the suffix ski, which implies land ownership (Internet Surname Database). There are several notable Americans with the surname Kowalski listed in Wikipedia.
As he is from the USA, Kowalski may have gone to the Ilvermorny School of Witchcraft and Wizardry.
From the Web
Screenshots of the Daily Prophet's coverage of the 2014 Quidditch World Cup: http://imgur.com/a/AXutv