Considering the transfer ban means they'll presumably be forced to play a load of younger players over the season, who will respect Lampard, & have worked with him directly in the past, it's not the worst idea in the world.
Tactically in big games is where the issue will inevitably come, but if you can install a team alongside him with experience it could actually be a workable stopgap solution for a season or so.
Hopefully it'll go horribly wrong though.
Inexperienced manager that hasnt conviced anyone so far and a team that has just lost their best player with a transfer ban hanging over them, I hope it all goes to hell.