It was starting to look as though we might never hear from defenseman Erik Gustafsson again.

After his gaffe in Game 7 of the Blackhawks’ first-round playoff series against the Blues in 2016 led to Troy Brouwer’s winning goal, Gustafsson — who was expected to be a key player from the start the next season — was banished to Rockford of the American Hockey League. He spent the entire 2016-17 season and half of this season there.

Those costly errors tend to stick with coaches. When Hawks coach Joel Quenneville was an assistant with the Avalanche in the 1996 playoffs, defenseman Craig Wolanin committed a turnover in overtime in Game 3 against the Hawks that led to a game-winning goal by Sergei Krivokrasov and put the Avs in a 2-1 series hole. Wolanin never saw the ice again, and the Avs went on to win the Stanley Cup without him.

In overtime of Game 7 of the Hawks’ first-round playoff series against the Canucks in 2011, Chris Campoli committed a similar turnover that led to Alex Burrows’ series-winning goal. Campoli never played for the Hawks again.

Gustafsson’s neutral-zone giveaway wasn’t quite as egregious, but he committed somewhat of a cardinal sin in Quenneville’s world by trying to carry the puck up the ice instead of passing it.

‘‘We had the perfect setup there, and we did exactly what we’re not supposed to do — or what we’re not accustomed to doing — and it’s in our net,’’ Quenneville lamented after that game.

Perhaps it was only coincidence, but Gustafsson didn’t play another shift with the Hawks after that mistake until he was recalled from Rockford on Jan. 9. But the Hawks have been rewarded for their patience, and Gustafsson has been rewarded for his perseverance. With two assists in the Hawks’ 3-1 victory Sunday against the Bruins, Gustafsson has two goals and six points in four games since signing a two-year contract last week. He has a plus-10 rating in his last 10 games.

‘‘It’s a coincidence,’’ Gustafsson said about his scoring output since signing the contract. ‘‘Of course, I’m more relaxed, but I don’t think it has anything to do with the contract. I’m just trying to skate a lot and move the puck quick, on the rush.’’

Gustafsson, who will turn 26 on Wednesday, is showing indications he is finding a sweet spot in his game and giving the Hawks the offensive production they’ve lacked from their defensemen for most of this season. Gustafsson has been on the ice for 12 of the Hawks’ last 14 goals in regulation. (He has been on the ice for five of their opponents’ 18 goals in the same span.)

Though he still needs work defensively, Gustafsson has the potential to take his game to another level with his offensive ability.

‘‘I think maybe play my own game a little bit more,’’ he said. ‘‘I’ve been trying to pass the puck too much a little bit. I think I can shoot it a little bit more and create some more offense in the offensive zone. Try to just play a simple game in my own zone and join the rush as much as I can.’’

Gustafsson, who has three goals and 11 points in 23 games since being recalled, is making a believer out of Quenneville. He has used Gustafsson on the power play the last two games, including for more than five minutes in the victory against the Bruins.

‘‘He’s got some good offensive instincts coming out of our end,’’ Quenneville said. ‘‘Makes a lot of direct plays. And him at the point . . . that’s a great strength in today’s game.’’

Follow me on Twitter @MarkPotash.

Email: mpotash@suntimes.com