I find this to be well ranked based on the unknowns that we have.
Freshman OL usually don't start very well. Mauigoa is the exception the same way Sewell was, and that's why they were drafted Top 10. Cantwell is a question mark till proven otherwise. We don't know who'll start at C, as Rodriguez is a question mark with his health. We don't know where Samson will play. Meriweather was brought in and we don't know whether he'll start. McCoy hopefully is into shape enough where he can play games without being subbed all the time. Buchanan made noise, but we don't know what happens with him once the lights get turned on.
I trust Mirabal, but we have a lot of unproven commodities by a pure preseason look. It'll change after the first week, probably, but till then - the picture is what it is.