The Scotland hitman had his shooting boots on again at the DW Stadium, scoring twice in a 3-2 win that moved the Wearsiders into the safety of mid-table. It took Fletcher's seasonal tally to 10, more than a third of the 27 Sunderland have scored this season.
"We relied on him way too much earlier in the season," said Larsson. "We all have to chip in, which would give him a bit more space as well as opposition teams have other players to worry about as well."
Wigan are evidently one of Fletcher's favourite opponents given he has now scored six times against them in seven games.
His latest brace was impressive, rattling home the first from close range after Ali Al-Habsi had saved his header, then curling Adam Johnson's knockback in from the edge of the area just before half-time.
"Six in seven is not a bad record," said Larsson.
"Fair play to him, they were two great finishes, both instinctive finishes.
"Steven's overall play, the way he can hold the ball up and his link play are very important for us."