Lampard made nine changes from Sunday's goalless draw with Tottenham in the Premier League and was rewarded with fine showings from fringe men like Emerson Palmieri.
The manager said: "The recruitment and now the competition has started to be really positive in the group, with players trying to get in the team and train at the top level every day.
"I have to put a small warning next to that because people will get excited, particularly after a result like in Seville but, as always, consistency is what wins you titles, Premier Leagues and Champions Leagues.
"We can't play like we did on Wednesday and then drop the level. Sustaining that level is what will bring success."