I'll give it a shot! I'm no expert, but I am a Westlake season ticket holder--have one graduate and 2 current juniors there, and one of my twins is in the band. So, yes, I'm a band parent, but I don't leave after halftime...
First, like you, I'm not looking past Edinburgh Vela. However, say that perhaps Westlake advances past them, then I'm expecting a matchup with Brandeis for the Region IV final. Lucky you, you get a virtual home game with your valley opponent, and somehow Westlake has to travel down to Corpus Christi for our game...
Westlake is a typical spread offense team. They typically line up in 1 back sets (probably 60% of the time), sometimes in 2 back, and occasionally empty. Regardless, Westlake runs the ball a lot for a "spread" team--you can almost guarantee that it's a run play when in 2 back. Overall, Westlake is very balanced offensively--217 yards/game rushing, 218 yards/game receiving.
Offensively, they run zone read a lot, and the QB Anderson (jersey #6) keeps a lot and is a surprisingly effective runner (barely 5'10", slightly built, but gets yards). He's the 2nd leading rusher on the team. As a passer, he favors the long ball, sometimes to his detriment (he floats a number of deep balls). But Westlake also has an effective screen game, too. They'll run, run, run to suck up the defense, then throw a wide-receiver screen that'll go for good yardage. Defense has to play assignment football.
Westlake's #1 tailback is Graham (jersey #29), and he's a good between-the-tackles runner. He's not fast enough to run much outside, but he gets good yardage. His knee got tweaked in the last game; I think he's playing, but we'll see. They did protect him a bit against Brennan, but Westlake got a huge lead early and was shutting them down defensively, so he wasn't needed as much. But he's averaging over 100 yards/game.
Westlake's two primary receivers are Baker (jersey #2) and Mangum (jersey #11). Baker often plays slot, but he's the primary deep threat (he's not always in the slot). Mangum is more of a possession receiver, but he'll too go deep.
Finally, they've got a good place kicker who is effective from 40 yards in (and has made a couple longer). Punting is OK, but Westlake hasn't punted a whole lot this year. I've seen them pooch it with the QB almost as often as trotting out our regular punter (same guy as the place kicker).
There aren't a ton of stars on the team--Westlake's offense is effective because of scheme and execution.
Defense is the primary strength of the team. Westlake's opponents are averaging under 9 pts per game. Westlake shut out 4 district opponents (including Bowie, who was Judson's 1st-round victim). Most opponents scores have come in garbage time against the 2nd team. Westlake was leading Brennan in the last game 49-0 until the 7 minute mark of the 4th quarter. They held Lake Travis to 14 (both by Wilson--one long pass for a TD, and another a KO return where we inexplicably kicked off to him...).
The front 7 is the strongest part of Westlake's defense. David Neil (sip o-lineman Dan Neil's son) is a very active DE, and he's quick. So is Sam Ehlingher's little brother, Jake, who's an LB. Really, the entire front 7 is fast. The secondary can get (and often does get) beat. However, Westlake is very aggressive on the pass rush, so high-school QBs often have trouble getting the ball out to their often open receivers.
That is the way to beat this defense--use the aggression against them. Screen passes wide are sometimes effective, as are sweeps (if you've got the speed to get past the defensive front). Also, again, if the QB has time, you can pick apart the secondary.
Hope this helps! Now tell me about Brandeis. Good luck against Hanna, and congrats on beating Steele.