Enter Raph, pt II.

What's the biggest difference between those top-tier professional bands and your band? They have mastered the art of ensemble playing, while members of your band are still buried in their own parts. They are a phalanx of Greek soldiers, moving as one unit to crank out an incredibly tight wall of sound. 

What is that on the shield? A peacock? An emu? 

Your band is usually more like this gathering of Greeks:

What do we want? Steady tempo! When do we want it? Now!

...but on bad days it can look like this gathering of Greeks:

The beat(ing) goes on.

Why is this? They have a solid command of the top of this pyramid, while some members of your band are hardly aware of it:

Pyramid power!

All of us in amateur bands have a solid enough technical base, although the occasional fast and dense passage may trip us up (more on that soon). There are probably some minor deficiencies when it comes to stylistic interpretation of written jazz and swing music. And if that's the case, forget about the top level entirely. Unfortunately, that's what makes your band sound loose and inconsistent.

Most amateur bands need to work on the middle slice of the pyramid as individuals, then the top slice as a group. Dance Band Reading and Interpretation by Alan Raph provides a common reference to do that. See the Google Books preview here. Practice the etudes alone at home to make sure Raph's five rules are being consistently applied. At rehearsal, don't do the usual warm up on an easy tune, but get more accomplished by warming up with ensemble playing of a couple etudes, striving to match each other's style. Done consistently, the band will start to sound better and better as they play more as an ensemble and less as a mere gathering of individuals.

If you've never experienced playing in a group where that pyramid is fully present, start watching YouTube videos of the Basie band, the SWR Big Band, or Gordon Goodwin's Big Phat Band to get a taste for what it sounds and looks like. Do those exercises in the Raph book with your band and you'll start to know what it feels like. There's no going back after that!