At the moment Lampard's problem is to understand the new players. They need adaptation and at the moment they are not a good team. So I wouldn't expect much on Lampard to bring Chelsea better. No worse than potter, maybe that's my best expectation. In the UCL I think they also don't have as much hope as they will be against Real Madrid.
I'm sure Chelsea will look different if they are handled by a world-class and experienced coach, although if they were brought in at this time they would not be able to lift the team's morale in the Premier League again. But I believe they have a big chance in the Champions League. At least if it wasn't for the caretaker coach who was in charge of the current team, Real Madrid wouldn't be able to rest easy for the quarter-final match. But if with the current conditions, then Real Madrid will easily crush them.