I do agree that this is part of it. However, I also think the team may want to build up their own confidence in Ronning.I have to believe that part of the reason for leaving Ronning where he is, is to get his confidence back up.
Like when Chytil earlier in the year wasn't playing a whole lot (in terms of minutes), Quinn kept saying he needed to find ways to get him more TOI. They knew they had an NHL-caliber player on their hands and needed to make an effort to get him more action. Ronning, they also said they need to get him playing, but it wasn't by way of trying to adjust the AHL lineup to get him more minutes and opportunities, it was just demoting him to the ECHL. Obviously, Chytil and Ronning are in vastly different tiers of prospect, but still.
I think that if the organization really felt that Ronning was ready for the AHL, then they'd try to work him into the mix. As I said, there are a few guys that are clearly not in the long term plans that are playing ahead of him. If they really wanted him getting AHL minutes, they'd make it happen. I believe they're just not sold he's ready yet. Playing in the ECHL isn't great, but it's not a death sentence. Hopefully he can work his way up and make some noise in the second half.