I rate lampard as a manager personally, i think he gets a lot of unfair criticism.
Derby - very nearly brought them up, lost in the play off final
Chelsea - finished in the top 4 when they had a transfer ban, brought through likes of reece james, tammy abraham etc.
Everton - basket case of a club at the time and kept them up
Chelsea (caretaker) - terrible run but the club was in a mess, i personally don't pin any blame on him for that.
Coventry - Play off finish after picking up a team near relegation places, then won the league the year after
I think if he went back to chelsea now he'd do very well