Bradley Wright-Phillips and Marcello Trotta were on target as Crewe came back down to earth with a bump following Sunday's JPT final triumph at Wembley.
Rosler said: "The players went into the game focused on the job in hand and they have put us in a fantastic position now.
"We made 24 attempts which says it all. We clearly deserved to win, there is no discussion to be had about that.
"We always talk about attacking and we succeeded with very good movement up front while the back four were terrific. Everyone played very well and we had so many man-of-the-match performances.
"Marcello looked very good in training. He is young and struggles with playing every three days but he always shows the right attitude and I believe in his qualities."