Drafted by Washington in the second round of the 2019 NHL Draft, Leason now has 3-3=6 points in 19 games this season, his second as a Duck.
Carlsson has points in two of his last three appearances (1-1=2) and 10 points in 15 games this season.
The period would go south from there for the Ducks though, as a pair of goals from Wilson 2:45 apart and another from Dowd on the very next shift put the Capitals up two after one.
Playing in his 700th career NHL game, Wilson leveled the score on a breakaway move to the backhand after the Ducks turned the puck over just inside the offensive blue line.
Now the third longest-tenured Capital after defenseman John Carlsson and captain Alex Ovechkin, Wilson has scored in each of his last three visits to Honda Center.
The physical veteran forward scored again on a tough break for the Ducks, a power-play one-timer by Ovechkin that kicked off Radko Gudas' foot and right to Wilson on the backdoor.
Wilson is second among Capitals team leaders in goals and third in points (7-5=12) this season.
Dowd capped the exciting, albeit sloppy, opening frame with a deflection of Sandin's point shot that fluttered over Gibson's left shoulder.
The goals suddenly dried up after a wild first period though, as Washington led 4-2 until the eight-minute mark of the third period, when McGinn somehow spun and tipped home Leason's wrister from the slot all in one motion to bring Anaheim within one.