The Reds boss gave a number of fringe players the chance to impress in Sunday's FA Cup fourth-round trip to Oldham but they were out-fought and slumped to an embarrassing 3-2 defeat.
Rodgers sent Gerrard on in the second half and the captain almost inspired a fightback at Boundary Park, hitting the bar with a fierce strike that would have drawn Liverpool level, but the damage had already been done.
Rodgers said: "This is a harsh school. This isn't a club where a young player can come in and have lots of time to settle, this is one of the biggest clubs in the world, so you need to understand that every game you play is a cup final.
"And we had one or two that were too soft, simple as that. If you want to have a career at a club like this, you've got to be tougher.
"It was only when Steven Gerrard and Stewart Downing came on that we played anywhere near the intensity and tempo that we would expect. When you get the opportunity, you have to take it. If not then it can be very difficult for you."
On Gerrard, Rodgers added: "He absolutely flipped the game on its head. It was fantastic but he does that every day of his life, and that's why he's a world-class player.
"Our young players, they won't have a greater role model to follow, and they're in pole position to learn, because they're seeing him every single day.
"If they're bright enough, they'll learn from him, and then hopefully they can be here for a long time. If not, they might find themselves playing in League One later on in their life, and they'll regret the opportunity they had of looking at a world-class player every day and learning."