The Tall Blacks swingman set the tone for the night with the Hawk's first bucket - a corner three on the fast break.
Both teams scored 29 points in the first quarter as Sharks guard Mojave King (29 points, 7-14 threes) got off to a hot start.
Southland led 51-50 at halftime with Hawke's Bay keeping touch thanks to offensive rebounding and a 14-4 advantage in second-chance points.
The Hawks leapt ahead in the third quarter, finding their best offensive rhythm since guard Jarrod Kenny (eight points, game-high eight assists off the bench) and Tajuan Agee (13 points, 11 rebounds) joined the team last month.
Downer said the eight-day break before their next game at home to the Taranaki Airs on June 18 presents a chance to have some consecutive practice and further bed the latecomers in.
"Hopefully, [we] get into a rhythm and that's where maybe some of the chemistry will build a little bit more," he said.
"That's the challenge now, not to relax but to keep growing and keep building."
Downer was unhappy with the defensive effort overall, although noted his side kept the Sharks to just 15 points in the fourth quarter.
"That's two games in a row we've given up 50 points in the first half, that was really quite frustrating," he said.
Guard Derone Raukawa (11 points, four rebounds, four assists, four turnovers) had a quieter night, but hit three of four three-pointers to keep his hot streak going.
Hyrum Harris (19 points, eight rebounds, six assists) made his typical all-around impact in a tough matchup against Tall Blacks teammate Dominique Kelman-Poto (24 points on 11-12 shooting).
The Hawks' sixth win leaves them third on the NBL ladder at the halfway mark of their regular season campaign.
