From Endless Abyss: 602h1m
Hatogaya, a man who loved baseball and yet left it, is set up to take the fall for his company and gets sent to prison. A high-school principal and his former coach whose school is about to lose its baseball program bails Hatogaya out. But, in exchange for getting him out of jail, he has to coach the schools not-so-great baseball team.
44 Volumes (Complete)

This is without doubt the greatest baseball manga i've ever read, even including adachi mitsuru's works.Very interesting in its emphasis on baseball tactics and mindgames and telling the story from the coach's point of view.
If more chapters were out a better idea of this manga could be established, but so far it seems like a bit of GTO + Touch, but without a lot of character development or romantic subplots that would make this a complete manga. Hopefully more of that will be seen in the future.