HOUSTON -

The Houston Texans ushered in the Bill O'Brien era Tuesday when veterans and rookies were on the field together for the first time on the opening day of organized team activities.

Other than injured players undergoing rehabilitation, the only player missing was unhappy receiver Andre Johnson, who was a no-show during the offseason.

Johnson, who turns 33 in July, has three years left on his contract and is scheduled to make about $11 million this season. He hasn't said publicly what the problem is, claiming it has nothing to do with his contract and insisting he hasn't asked to be traded.

The Texans know but aren't telling. Obviously, they would like their seven-time Pro Bowl receiver to meet his new coaches and quarterbacks and learn the new system.

What is known is this: Johnson won't be traded or waived. And with $11 million on the table, he won't be retiring at 33, especially considering he is coming off back-to-back terrific seasons, 109 catches for 1,407 yards last season, 112 for 1,598 yards in 2012.

When Johnson's weekly paycheck of more than $648,000 is issued during regular season, it is doubtful he will stay out -- no matter what kind of burr he has under his saddle.

O'Brien, who has spoken to Johnson several times, reiterated what he told the media during the rookie minicamp.

"Like I said last week, I'll let Andre speak for himself," O'Brien said. "I said last week that he and I have had positive conversations. I have a ton of respect for him. We'd love to him here right now, but that's up to him.

"Again, we're moving forward with the players that are here. These guys that are here are working extremely hard."

The bottom line is that the Texans don't need Johnson in the OTAs. This will be his 12th season. He always is in outstanding shape. When he reports, he should have no trouble picking up the new system.

However, he must stay in shape. Working out on his own is one thing, but getting in football shape with his strength and conditioning coaches is something else. He can't afford a season interrupted by hamstring and groan injuries.

Meanwhile, DeAndre Hopkins, last year's first-round pick who started opposite Johnson and caught 52 passes for 802 yards, becomes the primary target in the offseason.

Keshawn Martin and DeVier Posey, both of whom are entering their third season, will get more repetitions. More reps mean more opportunities to impress the coaches.

O'Brien said the starting quarterback job is wide open, but it would be a huge upset if veteran Ryan Fitzpatrick isn't the starter over veterans Case Keenum and T.J. Yates and fourth-round pick Tom Savage.

"They're all doing a good job," O'Brien said. "It's not easy to learn a new offense, especially when you've been around awhile (like Fitzpatrick). I've seen a lot of improvement every day with that whole group.

"I think, initially, in this part of the year, you have to make sure that the reps are equal, and you've also got to make sure that each guy gets a chance to rep with the starters or the guys that are running with the first team. We try to make sure that we have equal reps, and when we get to training camp, we'll make a determination on who gets the most reps to get them ready for the game."