I attended and was in the Richland band recently so I might be able to shed a little light on it.
Richland just absolutely killed it in finals. I've never seen anything like that out of Richland. They looked like a top tier band like you would see out of the top 3 at a super regional or something. Their brass was incredibly powerful, much more so than Marcus. Their DCI instructors are starting to show through. I totally could not believe my eyes and ears. It wasn't a judging anomaly or anything, they just popped off an incredible show. They have an incredibly demanding show that is hard to make happen and in finals they absolutely made it happen.
Richland's rise has to do with a couple things. In the past few years Richland has oversized their band. They had Freshmen marching who weren't ready and by the end of the year they always had multiple holes they couldn't fill. They had people switching and fudging instruments to make it work. This year they cut back on their drill numbers, they actually have a decent amount of non-varsity members, and it's made them a million times cleaner. They also hired a show design coordinator for the first time ever, and have new drill and music writers who are doing an amazing job.