The Saints won 76-0 at Langtree Park and Rush has stressed the importance of defending in his squad.
He said: “After the Widnes game, where we conceded points late in the cup tie, we spoke about defence being an attitude.
“When you have as many good players as us you aren’t doing tackle tech every day. It’s a mental thing, an attitude thing, and in the last two weeks we have proven that.”
Rush went onto praise Oldham, who had to switch their home tie from the Whitebank Stadium due to the ground’s facilities, and the Roughyeds’ attitude in the opening few minutes.
He said: “I thought Oldham had a real dig at us and we expected that. To be fair we weren’t the best in the opening 10-15 minutes of each half offensively and missed a few chances.
“We came up with some errors so we got the message to our 6, 7, 1 and 9 to get hold of the game. When they did that we got into positions we wanted to be and were dangerous.”
Rush and Keiron Cunningham have led St Helens to six victories from seven games since Royce Simmons departed the club, and Rush insists it could have been seven from seven if luck had been on their side against Wigan.
He said: “If we hadn’t lost Jonny Lomax early in the Wigan game then that would have been a different story.
“But we’ve had six good performances and the last two weeks have been pretty similar. At Castleford we had to defend for our lives and show determination. In our other games we have been more offensively strong and we are happy with where we are up to.”