Ramsey, 26, has made just eight Premier League starts this season, with niggling injuries holding him back.
The Wales international scored 26 goals across two campaigns in 2013-14 and 2014-15, but has been unable to match those tallies since.
Wenger said he had envisioned Ramsey being Arsenal's Lampard, who starred with his goal-scoring exploits from midfield.
"In my head Ramsey was going to be a player between 10 and 15 goals a year," he said.
"He is a Frank Lampard type. He is [about] getting in the box and he has a huge capacity to run. Physically, he has a combination of stamina, power and his capacity to repeat high intensity is certainly the best in the league.
"This season has been very frustrating for Aaron. I looked the other day, he has started seven games in the Premier League.
"When I realised that, it was unbelievable, but it's because of injuries – and not big ones. Every time it's a niggling one and when he came back from those – boom – a little calf – boom – a little hamstring."
Ramsey was their hero in the 2014 final, scoring an extra-time winner against Hull City.
Wenger hopes the midfielder is ready to play a big role to finish the campaign, saying: "He looked fit on Monday but I hope he will have a strong end to the season because he is an important player for me.
"He has it all in the locker to be defensive and offensive. So that is for me a vital part of the game we want to play. We do not only want to defend, we want to defend and attack.
"These kind of players are very important. I also think he is at his best age as a midfielder when you look at it at the start of the season. He is a player who can take the role of Mesut Ozil.
"When Ozil needs a breather you can play Aaron there, but he was not there earlier this season."