This week I'll take a look at the Texans' process for evaluating and coaching quarterbacks. We'll preface that project today with a look at Texans coach Bill O'Brien's philosophy on player specifications.

HOUSTON -- Upon his arrival in Houston, Texans coach Bill O’Brien made clear the team was going to get bigger, tougher, stronger and smarter.

That's taken discipline and a very clear vision for the team.

"This year ... and I would say last year, we really stuck to our beliefs in basically what type of, the body type of a player," O'Brien told me. "... You’ll see a bigger team, a longer team, length of arms, length of legs, athletic ability. You’ll see a different looking team."

There has been a difference, especially on defense.

According to ESPN Stats and Info's David Kiarsis, defensive linemen acquired by the Texans with O'Brien as head coach and Romeo Crennel as defensive coordinator average 23 pounds heavier than those acquired through the draft or free agency by the Texans when Wade Phillips was defensive coordinator. The difference there when you only count draft picks is 14.5 pounds. Drafted defensive linemen averaged arms a full inch longer with Crennel as defensive coordinator than with Phillips. Defensive backs acquired in the past two years average nearly two inches taller than those taken when Phillips was here.

Size and length are especially important for defensive players and offensive linemen. Intelligence is important for offensive players, but physical requirements also play a part. The Texans like quarterbacks with big hands and Ryan Mallett's 10.75 hand span at the combine in 2011, was the largest of any quarterback that year. O'Brien and his staff define each position, down to size measurements, speed requirements, and other tangible attributes with rigid specificity, then share those definitions with general manager Rick Smith and his staff.

The process started the January O'Brien was hired with hundreds of hours of meetings between O'Brien and Smith, some of which involved film study. O'Brien is known throughout the league as a coach who values scouts' opinions, and he expressed as much in our conversation. Smith declined to be interviewed for this story.

“That’s a hard process; that takes a while,” O’Brien said. “That doesn’t happen overnight. … There’s always going to be some differences of opinion. For the most part you want the scouts and coaches to see the players the same way. Once you get to that point, now you’ve got something special.”

Armed with positional specifics, the Texans’ scouts scour the country for players that fit. Coaches join the fray once the Texans’ season ends, poring over the lists those scouts have provided to choose which players they'd like to see in person. This season O’Brien made a concerted effort to send his position coaches to more pro days to get closer looks at players.

"I think Rick and his scouts did a really good job of telling us how they saw the guys," O'Brien said.

The discipline in setting parameters for each player is something O'Brien learned from various head coaches he’d worked for in the past -- his three mentors were George O'Leary, Ralph Friedgen and Bill Belichick -- who required players to fit certain parameters before drafted into the NFL or recruited to a college team.

The adherence to size specifications is also one shared by other personnel departments, especially ones with similar pedigrees.

“Big picture wise, you want to play with the odds not against the odds,” said Ed Marynowitz, the Eagles vice president of player personnel before the draft this year. “The odds are telling you that the majority of these guys that are under this certain prototype do not play at a starting level in the NFL.”

Marynowitz has ties to Bill Parcells, as does Bill Belichick, one of O'Brien's mentors, and Texans director of player personnel Brian Gaine. Marynowitz also worked under UCF coach George O’Leary, another man O’Brien considers a mentor. The head coach Marynowitz works with, Chip Kelly, is a friend of O’Brien’s.

There is some subjectivity to the process.

“If a [defensive back] has really good coverage skills, but only has 28-inch arms, they really have to have really good change of direction,” O’Brien said. “If he has 31-inch arms, he has a real good chance to break up a pass in tight coverage. An outside linebacker, if he has longer arms he has a really good chance to get his hands on the tight end and set the edge faster than the tight end can get his arms on him.”

Cornerback Kevin Johnson, the Texans’ first-round pick this year, has arms that measured 31 inches at the NFL scouting combine. Outside linebacker Benardrick McKinney, who the Texans took in the second round, had arms that measured 33 inches.

“Let’s say you have a linebacker that maybe doesn’t quite meet your height requirements,” O’Brien said. “Let’s say inside linebackers need to be 6-3 and above and this guy might be 6 foot 250 pounds, but man he’s a hell of a football player. You make an exception from a height standpoint.

"You just can’t have too many exceptions. If you have too many exceptions you have a team that’s not quite as big as you want it to be. You have to keep track of how many exceptions you made."