Alex has a fairly solid K rate, around eight per nine in AAA, and doesn't walk too many (around 3.5 in AAA). He simply didn't get a real opportunity in the organization he was in. Don't be surprised if he comes back from Japan and puts in a few seasons in the bigs with someone.
Not wanting to seem lazy but how many MLB pitchers have come through the minors in the US than gone to Japan and come back as an MLB quality pitcher? I don't think I have heard of this before