First, I don't get the promote him piece. He doesn't deserve it right now. He's still a great prospect, but he's getting hammered. He had control issues last season as well, and I suspect that what he's doing is working on that at the expense of his stats. That might suck for us watching the box score, but this is something he needs to figure out... and soon.
Second, no pen just yet. He has 3 options, with this year being his first. I have zero issue letting him figure out things as a starter. Short term pen stint at some point? sure, but I want him building up that arm strength anyways.
Third, from what I read, the velocity is still there... Problem is that the pitches are hittable. He's just missing his spots, and it's enough for him to get shelled. That will probably come around, we just need to be patient. The nice thing is that we have 2 younger guys doing well in Gibson and May, with several more on the cusp. The Twins can afford to be patient with Meyer, a callup now isn't going to fix him, it's likely going to make things worse.