We don't have anyone that can 2-Gap anymore. I don't even think Pennel can 2-Gap. Raji certainly can't, and never could; so, of course their roles have to be different.
If you put Daniels in there and expect him to hold up against a double team?? Forget it, of course he'll get run over... which is one of the reasons you don't want to run a 2-4 with the personnel we have.
If you have 3 down linemen inside the tackles - everyone can look to penetrate and control their single gap, and defending the run becomes a much more doable proposition while in the nickel.