The Bees manager said the strength in depth in his squad was the reason for their win and further evidence that the club has what it takes to challenge for a top two spot.
Two inspired second-half subsitutions helped, with winger Stuart Dallas tormenting the visitors and Tom Adeyemi breaking the deadlock with his first touch.
The Bees, without 20-goal striker Clayton Donaldson and suspended Adam Forshaw, always had enough in reserve to dominate the game.
The stalemate, created by a resolute Iron defence, was ended with 20 minutes remaining when Adeyemi coolly side-footed home from 10 yards after good work by Marcello Trotta.
Rosler said: "They helped change the game for us, but we also had young Jake Reeves out there who did extremely well.
"We had energy and freshness in the legs and head and played at a good tempo and a lot of that is because we have a squad of players who have all proved their worth."
Rosler added: "I don't look at who is in the team. I look at who is in the 18 because that strength in depth and ability to rotate and still keep getting results is what will dictate who finishes the season the strongest."
Rosler admitted he now has a selection headache ahead of Tuesday night's trip to Stevenage, with Donaldson in contention again.
Brentford created enough chances - 17 efforts on target - without the big forward, who was replaced by Trotta and Bradley Wright-Phillips.