It appears there is some confusion as to the actual enrollment of SIU. The article on Vindy.com this morning lists the enrollment at about 30,000 students. But, that is far from the enrollment listed on the SIU website. Based on what you posted, it appears the 30,000 is including the campus in Edwardsville.
I just went onto the SIU-Edwardsville website, and you are correct the school has a Chancellor at not a President. SIUE had an Undergrad enrollment of 11,341 according to the web site. Data is for Fall of 2012.
I thought SIU-Edwardsville would have had their own President, but apparently that is not the case. Thank you for clarifying.
SIU is a research University, and the SIU system does have a Medical School and Dental School. I can see how that might make for a more attractive position for a President. Dunn also has Bachelor's and Masters Degrees from Illinois State, and a Doctorate from U of Illinois. So, in a way, going to SIU is sort of like going back home for Dunn. This type of thing happens.
For me, it is not so much that Dunn is leaving, as it is the way he went about keeping YSU in the dark on the possibility he might leave. I know some will not agree with me, but I think this situation reflects poorly on Dunn more than it does on YSU. Never a bad thing when the President of a University is wanted by other schools. Whether or not Dunn was a wise choice to begin with, I will leave for others to decide. Not an area of which I know enough about to say whether hiring Dunn was a good choice or poor choice.