As far as the musical qualifications, I agree with several of the other people that have responded. Many of these things can be learned or can be misleading on the resume. What I want to see is how effective they are at taking a beginner class through a middle school and high school program. How do they teach and break down the more complex concepts? In the end, it doesn't matter how good of a player the perc. director is but rather how good he/she can make the students.
Additionally, I think that there are some terrific percussion directors out there that also teach a competing band and do that as well as they teach percussion. This is who I would lean towards because it is indicative that they "get" band as a whole rather than percussion/drumline being independent. Granted, not all percussion directors have the opportunity for time on the podium due to scheduling, school size, band enrollment numbers, etc., but what I really try to filter out is the guy that scoffs at the notion of teaching a beginner trombone class because "it's not what I signed up to do." Those people are out there and do not make good staff members.