Our current cast-offs from other P5 programs on the OL haven't exactly panned out. Then look at a guy like Ersery. But most accounts he has performed well (albeit with some growing pains). Our type of program has to be a developmental program. OL usually take years of seasoning before they're ready for the B1G anyway. Get a guy like that in the program and in year 2/3/4 he should be ready for some action.
The portal works both ways. Look at all the guys that left last year. The majority of them (with some exceptions, like Anderson) were buried on the depth chart and either wanted to move to somewhere else where they could play, or were politely encouraged to move on. So you take a chance on a developmental guy, and if he pans out, great. If he doesn't, he is likely going to move to a lower level school anyway, and your problem is solved.
edit: Bob, I'm using your post to prove a point to the other user, completely agree with you.