Between 2015 and 2021, Slovenia reached the final of the European Championship three times and finished as runners-up on all three occasions after losing to France, Serbia and Italy, respectively.

[3] He led the team to its first medal at the 2015 Men's European Volleyball Championship, when Slovenia lost 3–0 to France in the final.

[7] Two years after his appointment, in January 2019, the Volleyball Federation of Slovenia and Kovač both agreed to part ways and terminate the contract.

The team reached the final, where they defeated Cuba 3–0 and earned the right to participate in the 2020 Nations League, replacing Portugal; however, the competition was cancelled due to the COVID-19 pandemic, and Slovenia qualified for the 2021 edition instead.

[18] After failing to reach the top 8 in the 2022 Nations League, he was sacked and replaced by Gheorghe Crețu in August 2022, just two weeks before the start of the 2022 FIVB Men's Volleyball World Championship, co-hosted by Slovenia and Poland.