Franck Lampard is a legend in Chelsea and even during the time when he was a player in this team he had a good performance also as a coach is suitable for his team because they can't have enough time to hire another coach, however, it was a big risk for Lampard to work in Chelsea because they don't have a good situation there is a possibility for them to even fail with their coach, Frank Lampard.
Chelsea may have no choice now, they are in hurry to hire a new coach. Frank Lampard has a close relationship with Chelsea because he is a Chelsea player, that's why Frank Lampard is appointed as an interim coach. I agree that bringing back Lampard to Chelsea is a big risk, he ever managed Chelsea but it ended with an unsatisfying result. Lampard may end this season with the same result as previously (bad result). I assume that Chelsea doesn't target anything, so they hire Lampard although this man has no good record as a coach.
Given the situation that Chelsea find ourselves in, I would rather take this approach with Lampard in as a interim, while they find a long term solution with the right calibre to take the club forward. It’s be Pathetic if he's even talking and eyeing long term because he that couldn't save Everton. This is just an indication that Chelsea have some confused set of owners.