Reasons To hire from a consulting firm 
I know that you pointed out some risks of hiring from consulting firms, but are there compelling reasons for us to consider people from those areas for internal roles?
In this post about the reasons not to hire consultants, I wrote that consulting firms do a fantastic job selecting the best and brightest from MBA programs. I believe that people within industry sometimes get a bit too focused on skill set vs potential.  Consultants are a fantastic option for those companies willing to make an investment in people.
Here are some reasons TO consider hiring a consultant into an internal industry role:
Fast learners/Problem solvers – the top consulting firms require that there consultants come up to speed very rapidly on client business issues.  If a consultant shows a track record of promotions and high performance ratings within their firm, chances are they are great problem solvers and are generating lots of value for their clients.  Most companies want this type of talent on their teams.
Professional services – to succeed within consulting, the individual needs to demonstrate exceptional client facing skills (diplomatic, responsive, team-oriented, etc.).  These skills translate to both internal and external roles.
  
High trajectory – consultants are constantly given more complex engagements and increased team and client responsibilities.  Often times the consultant is experiencing the increased responsibilities much earlier than their peers in industry. An individual who consistently performs with increased responsibility is an asset to both industry companies and consulting firms. 
There are many other compelling factors to hire a consultants such as; being skilled at change management, they are adaptable/flexible, and possess a unique toolkit for addressing business problems. 
I’m obviously a fan of the consulting background and encourage you to consider consultants for you senior opening even if you set the odds low of a consultant winning the job.