One of the major pieces in the annual football head-coaching shuffle has been set in motion, as Bill O'Brien's reported agreement with the Houston Texans is sure to have a ripple effect on the rest of the vacant positions.

According to ESPN, O'Brien has reportedly agreed to a contract that will make him the Houston Texans' new head coach, removing him from his position at Penn State. The deal is expected to be announced by the end of the week.

Every year, as the college football and NFL seasons end, some coaches are fired and some get better opportunities. Also every year, several teams with new vacancies have overlapping interests in potential candidates. Naturally, a domino effect takes place after the first coach signs.

O'Brien kept no secrets that his goal was to get back the NFL and he even had Penn State's athletic director David Joyner reduce the coach's buyout from $19 million to $6 million before the season started.

O'Brien also reportedly fit Texans' owner Bob McNair's ideal candidate. O'Brien was the offensive coordinator of Bill Belichick's New England Patriots and he coached the likes of quarterback Tom Brady and tight end Rob Gronkowski. He also succeeded at Penn State, leading the Nittany Lions to 15-9 record in two seasons, going 10-6 against Big Ten opponents.

In the wake of the Jerry Sandusky child molestation scandal, Penn State lost a lot of money, athletic scholarships and received a four-year bowl ban. Still, O'Brien managed to recruit one of the nation's top high school quarterbacks and led the team to two straight winning seasons.

The Texans were intent on a change. They fired Gary Kubiak Dec. 6, opening the position before any others did. They wasted no time pursuing their candidates either, scheduling meetings with O'Brien in his Cape Cod home.

Penn State now joins a group of college and pro football teams in need of a head coach. Now that O'Brien has made his jump back to the NFL, several more dominos will be ready to fall.