He very clearly does not have doubts about Moreno, Lallana or Benteke. Not sure what’s giving you that impression when they’re playing every game for him when possible.
I don’t think he has doubts about Mignolet either, although it’s harder to tell with a keeper … all I’ll say is Mignolet has been doing grand since Klopp showed up, no major disaster on his behalf, and Bogdan had an excellent cup game under him, but it didn’t encourage him to drop Mignolet and give him a chance.
I think he’s seen Joe Allen for what he’s always been, a decent squad player who fills a hole somewhere in midfield when needed, but should never be part of the first team plan.
Frankly, I don’t think he has doubts over anyone yet. Klopp strikes me as the kind of guy who loves anyone who simply tries their best for him and will always give them chances until they give up on themselves, the team, or the club.