Ramirez struck in last night's Capital One Cup win over Bristol City.
Perez said: "It was a great goal but we think the more important thing for him was the opportunity to play 90 minutes.
"He came late in the summer and joined late in pre-season and the breaks with the national team don't help him to get the best performances and it was good for him to play 90 minutes.
"All players have to be in the best physical performance, the best peak of form, to try to play in the team.
"There are different levels because not all the players have the same number of training sessions.
"For him we try to help and are doing extra training sessions to get the same level as the team.
"We try to do extra fitness work because it's not easy when you have less training sessions than the others but you have to combine it with other training sessions as well because in six or seven days between a game it's not possible training like in pre-season.
"We had different strategies in the past and we carry on to help him and the other players to get the best peak of form."