She and fellow Chasers Bogomil Levski and Nikola Vassileva were considered "less flashy" than those on the other teams participating at the tournament. However, they did win all three of their matches against New Zealand, Norway and Japan to get to the final (Pm).
Although the Bulgarian Chasers only scored two goals against a talented Brazilian side - and a Quaffle drop by Grozda led to one of the Brazil goals, Viktor Krum's capture of the Snitch meant that Bulgaria were the overall winners of the tournament (Pm).
Other canon notes and references
Stoyanka (Bulgarian: Стоянка) is the feminine form of Stoyan, from стоя (stoya) "to stand, to stay" (Behind the Name).
Grozda (Bulgarian: Грозда) is the feminine form of Grozdan, from грозде (grozde) "grapes" (Behind the Name).
From the Web
Screenshots of the Daily Prophet's coverage of the 2014 Quidditch World Cup: http://imgur.com/a/AXutv