No inside knowledge here - just your average fan. But I suspect there are several issues. Though it appears the Dunn team is very good at attracting sponsors for a race here and a race there, I would imagine the actual funds are much less than it would appear based on the size of the signage on the car. Certainly a big help, but more or less enough to keep the team out on the tour and not enough to lean on it enough to run 3 second passes consistently. I'm sure Dunn runs on a very strict budget and could run mid to high 3's with some consistency with more $$. That would at least get him in the show more often.
I'm sure driver experience comes into play at times, but looking at their run in Q5 yesterday, no driver issues there. It looked like a good, clean run for that team, just not strong enough to get below 4.005 or whatever the bump was.
I also bet, as very complicated as these cars have become, that Big Jim could really use an additional set of eyes and ears in the crew chief department as most of the other teams have.
Maybe we'll here from Eugene for some additional behind-the-scenes insight.