D-Line having only 4 that are not freshman is certainly a concern. I was looking at the recruiting class and we could have up to 7 incoming freshmen depending on how things close out during signing day. We will need several of those to contribute quickly. Hopefully a few of these will truly be studs from day one. The depth was probably the biggest issue this year.
With as good as Saban recruits and his focus on defense it is very surprising that we do not have more D-Linemen with experience ready to step in and be studs. Quality freshman can certainly come in and do it but to me it is not ideal when so many of them will need to be ready from day one. Less room for error or development where needed when they step on the campus.