With the monotony of Indianapolis’ annual contention for the AFC South stifled by Peyton Manning’s injury, Houston and Tennessee will battle for the division lead Sunday as we approach the season’s midpoint.

It’s only been two games — but so far, so good for the Wade Phillips defense in Houston. The Texans have been struggling for years to field a playoff-caliber defense, and the results have been far less than satisfactory. Enter Phillips as the new defensive coordinator.

Every Wednesday this season, the research staff at “Playbook” will be taking your questions through email (playbook@nfl.com) and on Twitter (@NFLN_Playbook, with #askplaybook hashtag), and answering them in this blog. Here is the first batch of questions we’ve selected.

The Houston Texans gave new defensive coordinator Wade Phillips reason to smile — and Jets coach Rex Ryan reason to scream — in Monday night’s 20-16 Houston victory, capping the NFL’s opening week of preseason action. Relive that game and more from preseason’s first week of games.

I’m excited to be taking in my first live preseason game of the summer tonight in Houston. Sure, it’s only the first tune-up for two largely veteran teams — the Jets and Texans — but there’s constant evaluation going on this time of year, and I will be paying close attention to a few factors, in particular while the starters are around.

The Texans struggled on defense last season, surrendering the fourth-most points (26.7 per game) in the NFL, and that led to two key changes.

NFL Network insiders Jason La Canfora and Michael Lombardi doubled up on the Around the League desk on Wednesday, taking a look at coaches considered to be on the hot seat.

Was proposing to your girlfriend during an NFL game the biggest blunder of the entire season? We count down the six biggest do-over moments of 2010.

NFL Network insider Jason La Canfora has the latest on the CBA negotiations, injury updates on Saints RBs Reggie Bush and Pierre Thomas, Browns WR Joshua Cribbs and Titans WR Kenny Britt, as well as the possibility of former Dallas coach Wade Phillips landing with Mike Shanahan in Washington.

Brian Baldinger, Mike Mayock, Charles Davis and Rod Woodson discuss whether the Cowboys can get any better under interim coach Jason Garrett .

Could there be more playing time on the horizon for Cowboys RB Tashard Choice? That is the word, according to the Dallas Morning News. Choice told the paper that he was going to be part of the Cowboys rotation this week against the Packers. But coach Wade Philips seemed rather ambivalent about the whole thing.

Charles Davis, Brian Baldinger and Mike Mayock examine what’s next for the Dallas Cowboys.

NFL Network insider Jason La Canfora takes a look at four coaches who he considers to be on the hot seat during or after the season: Marvin Lewis, Mike Singletary, Lovie Smith and Wade Phillips.

This has been a solid year for the Cowboys — a 1-3 start and whispers of them being overrated. While the casual, Cowboys-hating fan rejoices over this, fantasy enthusiasts with Felix Jones or Marion Barber on their roster continue to be baffled by the most befuddling running back situation outside of Kansas City and San Diego.

Any birthday is a good birthday, jokes former NFL head coach Bum Phillips, who recently turned 87 and is busy talking up his new book, “Bum Phillips: Coach, Cowboy, Christian.”