The Spanish striker finally found the net for the first time at Anfield and his manager believes he can gain confidence from finding the net in front of the Kop against Oldham
The 26-year-old summer signing from Celta Vigo opened his account for Liverpool in the 2-0 win over Oldham Athletic in the FA Cup third round on Sunday.
"They have to contribute. We can't rely on 11 or 12 players," Rodgers told reporters when questioned about his fringe players.
"Iago's goal was important for his confidence. It's difficult with a world-class striker [Luis Suarez] playing every week and getting goals, and with Daniel Sturridge supporting he's been the cover player for a lot of this season.
"It was good for him to get his goal in front of the Kop and hopefully that will give him confidence."
Liverpool struggled to break down their League One opponents at Anfield and it wasn't until Philippe Coutinho was introduced as a half-time substitute that the hosts looked like securing their place in the FA Cup fourth round.
"We hoped in a game like this we hoped to rest a number of players and give them that recovery period. A few of the guys have played hard games over the Christmas period, so the idea was for them to recover," Rodgers continued.
"But we also wanted to win the game. We didn't want a replay, so the second half was better. We were livelier and ended up with a good victory.
"I thought it would be a difficult game and I think you've got to give Oldham a lot of credit. They came here and made it very difficult.
"For us we were nowhere near the speed of our game in the first half. The tempo was too slow and we didn't create enough. In the second half we were a little bit better but it was always in the balance."
Meanwhile, Oldham boss Lee Johnson praised his side's effort and says his players matched their Premier League opponents at times during the clash.
"I thought we were good. I thought we worked our socks off in the first half. I thought we broke well and got ourselves into areas where we could have had shots," he said.
"We certainly didn't just park the bus. I thought our boys showed energy, especially when we went 1-0 down, and for a 20-minute period you may not have known which was the Premier League side.
"We had a couple of great chances and I'm proud of them."