The coaches really had two choices. A) work on some of the new stuff they have put in going into year two, or 😎 work mainly out of the base and see where some of the guys are at.
I am sure what the coaches took from this is how the front line worked and that they got work out of the base defense, and, how some of these LB's could do out of the base.
While the #1 DL all played together last year they did not line up how they are lining up this year so they need the work. Plus there is a lot of raw talent behind those guys including Harrell in terms of where he is at physically so they were able to get more information IMO out of the base defense on the front line then had they run a lot of other stuff.
The bottom line is they are going to have to line up and play well out of the base so they might as well emphasis that aspect of the D early on. Granted, they aren't going to look overpowering that way but individual evaluations are important right now.
"The train is leaving the station."