In what way? A lack in talent, knowledge, discipline, maturity, or any or all
of the above? All of those may not point directly back at Howell, but they do all point back to the coaching as a whole.
When you say it's a "personnel" issue, either the coaches didn't recruit well enough, or they didn't coach well enough. Now, there are 4-5 defensive coaches and several more guys involved in recruiting, so it doesn't all point directly at Howell, but as the DC Howell is where the buck stops.