I don't think there is any evidence yet whether the portal "helps us or hurts us"... My guess is, it may actually help us in the long run. While we may lose an occasional overachiever to a P5, we should be able to attract more highly regarded players out of high school. IE Guys looking for a chance to play sooner rather than later and show what they've got... It also opens up opportunities to poach kids that overachieve at smaller schools or in the FCS.
The thing that sucks about the portal is the fluidity of it. Likely gone are the days of recruiting kids out of high school, watching them earn playing time, and develop for 4 years. Kids that don't see the field by their sophomore year will bolt for the portal to try to find playing time, kids that are stars may bolt for greener pastures, etc.
As for JUCO, it is already killing that circuit. Lane Kiffin, Nic Saban and others have made such comments. Teams aren't bringing in JUCO kids because they can get portal kids that are already clear academically and have been at programs where they have been competing against FBS competition.