I prefer to be brutally frank. The worst that happens is that he is shell shocked that he is not the most beautiful princess on the block and he runs away. But laying the expectations clearly and unequivocally straight from the beginning avoids a lot of miscommunications afterwards and possibly reduces some posting traffic from disgruntled employees on workplace.stackexchange.com :)
Having said that, it's possible that he can be a team lead in some organization where the standards of performance are not so high. Eery organization has a more or less clear idea of what it expects in a team lead. Your organization has its own expectations, which are probably distinct than some random organization's expectations.
Blessed be the biggest frog in the pond, because it hasn't met the catfish in the river yet, and doesn't know what it could be in for - I understand that catfish love frog legs :)