The Texans defensive end said he noticed Mettenberger posted a few selfies this week, including one a couple hours before kickoff.
"I take my job very seriously, and if I was a rookie quarterback and a starter for my first time in the league I'd be a little bit more focused than that," Watt said. "Maybe he'll learn from it, maybe not, but we won the game and that's all that matters."
The Texans (4-4) snapped a three-game skid and beat the team they replaced in Houston for the fourth time in five games. Arian Foster ran for 151 yards and two touchdowns and also caught a pass for a score, topping 100 yards rushing in his fourth straight game for the first time he's done that in his career.
"He makes a lot of yards because of his vision," Houston coach Bill O'Brien said. "He sets up blocks well. He has great instincts. He's good in the passing game. It's all the things I've said from day one with him. He's tough and he's a big back. He's hard to tackle. He had a whale of a football game."
Mettenberger turned the ball over twice, finishing with 299 yards passing and two touchdowns. The Titans (2-6) go into their bye having lost two straight.
The Texans had given up 24 points in a single quarter each of their past two losses. This time, they trailed only 3-0 early before scoring 27 straight points.
They had no trouble throttling a Tennessee offense playing three rookies with left tackle Taylor Lewan and running back Bishop Sankey joining Mettenberger. D.J. Swearinger intercepted a Mettenberger pass in the second quarter to end the Titans' first drive into Houston territory, and Tim Jamison recovered the fumble after Watt sacked Mettenberger and popped the ball out to end Tennessee's first drive in the third quarter.
Houston led 13-3 at halftime, a lead that should have been much bigger.
Foster broke loose on a 34-yard TD where he cut back to his right and outraced the Titans to the pylon with 6:00 left in the first half to put Houston ahead to stay. He also caught a 5-yard TD pass and scored on a 1-yard run that he set up with a 43-yard run in the third quarter.
Bullock finished with three field goals, including a long of 49 yards.
Whisenhunt turned his offense over to Mettenberger, the sixth-round draft pick out of LSU, after the Titans had lost five of six with Jake Locker missing three of those with separate injuries. Mettenberger gave glimpses of his strong arm with a 48-yard toss to Kendall Wright and a 43-yarder to Nate Washington. The rookie had his first career TD pass on a 6-yarder to Delanie Walker.
The quarterback switch didn't fix Tennessee's other woes. The run game remains nonexistent. Three of the Titans' six penalties were on the offense, and not being flagged once in the second half counted as progress.
Notes: Fitzpatrick became the 41st quarterback in NFL history with 1,500 yards rushing. He needed 3 and got 12 on four scrambles. ... The Texans have allowed 10 sacks in the past two games. ... Whisenhunt said Titans WR Nate Washington sprained a joint in his shoulder. ... The Titans now have lost eight of their last 10 at home.
Copyright 2014 by The Associated Press