Through his career, Isa never finished on the podium, but he once finished in the top ten individually. It, a 10th place, came in Pokljuka in the third round of the 2009–10 season. Isa's best relay finish in the World Cup was an 8th in Ruhpolding in 2004. His best overall finish came in the 2001–02 World Cup where he finished 46th.