HOUSTON -- This is not uncharted territory, but it's close.

Bill O'Brien thought enough of Brian Hoyer to sign him to the Houston Texans. He thought enough of him to choose him as the team's starter after a five-months long quarterback competition. Now he's apparently changed his mind, having told Ryan Mallett he will start.

One of two things is happening here. Either O'Brien made a mistake in choosing Hoyer at all and admitted that mistake early. Or, O'Brien is now making a mistake in switching to Ryan Mallett because he isn't giving Hoyer, whom he praised one week ago, enough time.

Mallett's play will answer that question.

Whatever the prism for understanding this move, it's an unusual one. It signifies turmoil at the most important position on the field.

According to the Elias Sports Bureau, there have been 21 instances of a team changing starting quarterbacks after just one game since 2005. Most of these changes were made due to injury, though some injured quarterbacks never got their jobs back. Four were purely coaches' decisions and only one of those four teams made the playoffs.

In 2014 the Rams started Shaun Hill for one game before replacing him with Austin Davis. According to ESPN Stats and Info, they went 6-10 and did not make the playoffs.

In 2008 Tampa Bay benched Jeff Garcia after one game for Brian Griese. Griese went 3-2, the Bucs went 9-7 that season and they missed the playoffs.

In 2007 Cleveland opened the season with Charlie Frye, then benched him for Derek Anderson. Anderson actually did well, going 10-5 and leading the Browns to a 10-6 record. They missed the playoffs anyway. Frye was traded in the week after his first start. Current Texans defensive coordinator Romeo Crennel was the Browns' head coach at the time.

In 2005, Washington started Patrick Ramsey at first, then benched him for Mark Brunell after one game. Brunell went 9-6, and Washington did make the playoffs, the only group of the bunch to do so.

If the mistake was indeed O'Brien's and he is correcting it now, Mallett will prove that in his next few games. This team, after all, was considered all offseason as being just a quarterback away.