The problem is Shota's stuff figures not to play out of the bullpen. And half the bullpen is already swingmen anyway - we hardly need another one.
That's your statement, deeg, but I have no idea if it's actually true.
1. I'm guessing his current stuff figures not to play well in any situation. HR's are bad in any situation, his velocity is down a little bit, and if his location is off that will be problematic in any situation. So you're probably correct that switching him to bullpen isn't likely to make him excellent there.
2. But he could be used more situationally in the bullpen. Every start is a tie-game leverage, and Counsell wants to have starters stack up innings. Assuming he stays bad in relief, you wouldn't need to have him pitch as many bad innings? And you might not have him pitch the bad innings in leverage situations? And you might take him out faster if his location doesn't seem sharp?
3. Many pitchers do pitch better in relief. No pacing, adrenaline max, better velocity. Maybe he'd get 1-2 mph back in relief, who knows?
4. Maybe he is intrinsically better suited for relief? On season, his OPS-against 1st-time-through-order is .654, 3rd time through is 1.022. Career-wise is kinda similar, and career-wise his first 25 pitches he's been best. Composite stats may not mean that much, because he is what he is now, and each year he's been better in spring than in late summer. But even over several of his recent bad starts, like yesterday he's sometimes labored through some early innings without giving up tons of HR's, but then it's several innings in like yesterday that he starts serving up the multi-run HR's.
So yeah, I think just rolling him out there every rotation to labor, allow HR's, and lose games, I'd kinda rather roll the dice with Assad and his 3.29 ERA as a starter.