He was known for his outstanding reflexes, leaping ability and acrobatic style of play, as well as his controversial antics off the field, which also earned him another nickname, 'el Loco'.
In his early years, Guevara was a baseball and basketball enthusiast despite future national team goalkeeper Raúl Antonio García being one of his friends in school.
He was tempted to train with Coca-Cola by former national team goalkeeper Raúl Magaña and then joined Platense to make his senior league debut at 16 years.
In the first round, El Salvador lost to Hungary 10–1, and Guevara became the goalkeeper with the most goals scored against in a single match, a record that stands as of 2019.
Guevara is married to Flor de María and the couple have three children: Luis Ricardo, Ana Luisa and Gabriel Sebastián.