Mrtka is expected to play full-time with AHL Rochester during the 2026-27 campaign, per Bill Hoppe of the Olean Times Herald.
While the 19-year-old Mrtka was rumored to be expendable during the 2026 trade deadline if Colton Parayko was made available, he's expected to stick around in Buffalo's organization with AHL Rochester to begin the season. However, the 19-year-old blueliner can still return to the WHL if it is considered the best route for his development. The ninth overall selection from the 2025 NHL Entry Draft flashed his offensive skills at the junior level last season with a goal and 33 assists across 43 regular-season appearances with WHL Seattle. Mrtka profiles more as a defensive force and will look to carve out a regular role in the AHL ahead of his age-20 campaign, but he also has a chance to debut in the NHL by the end of the 2026-27 campaign.