To me, it seems like ramping it up several times a week, sometimes 2-3 days in a row, would be more wear and tear on the arm than pitching once every 5 days, but I honestly don't know.
That said, it seems that it's not a decision between having Eovaldi in the bullpen or in the rotation, but it's a choice between having Eovaldi in the pen now or having him in the rotation maybe a month down the road. That being the case, I think we would all choose having Eovaldi now.
Also, Eovaldi is fully on board with going into the pen for now. He stated that it's partly his fault that the pen is in the shape that it's in, and it's his duty to help fix the pen. I believe he also sees himself as returning to the rotation sometime later this season.
All that said, we need a 5th starter no matter how good Eovaldi might be in the pen.