True, he might also be thinking that taking the job at the hardest possible time, with transfer ban, without Hazard and when he's probably going to have to entirely change the style of play (unless Lampard Ball?), when he's never managed a single game in a top league, is not a good idea.
Plus if he's not good enough for Derby he'd be unlikely to make a 2nd season with Chelsea, so hardly missing the opportunity.
We'll see what happens this week I guess.
Edit: It worked for Madrid with Zidane, which at the time also looked pretty crazy given he never did anything with Castilla. So maybe Lampard will be lifting the CL at the end of the season. Football is a crazy sport sometimes..
Lack of confidence is not something people like Lampard deal with. If he's offered it, he'll accept.
In terms of top level players getting chances before they've "proved themselves" there are more Gary Nevilles and Thierry Henrys than there are Zidanes and Peps for sure though.