I've heard several times during local Tigers broadcasts that Dombrowski thinks that Ledezma was the best pitching prospect in AA this season (of course we know that was a bit of a stretch, because I can think of at least two better prospects off the top of my head). That shows that Dombrowski likes him a lot.
Last year, he was kept in the majors for the whole season despite not being ready, because if he was sent down, he could have been lost to the team he was drafted from. Then this year, they were able to keep him down in AA to get some good work in. And it is true that he is going to be shut down soon, but he is expected to be a major candidate for the rotation next year.