I think it's too low and I think you'll see it rise during the preseason when people get a good look at this depth chart.
PFF is pretty good, but I think a lot of these folks just base their current rankings on what a team did the previous year, without considering above or below-the-mean performances, injuries, schedules, additions, subtractions, etc.
It was the same with Atlanta last year. That was a pretty good roster that went 8-8 in 2015. Still, they were pretty consistently ranked in the low 20s this time last year.