Veteran Santiago is a tight fit

FOXBOROUGH -- Bracing for the possibility of playing without injured tight end Benjamin Watson, the Patriots added depth at the position yesterday by signing veteran O.J. Santiago.

Santiago, 32, has played in 78 games (60 starts), suiting up for the Falcons (1997-99), Cowboys (2000), Browns (2001), and Raiders (2003). He was with the Broncos in 2004 training camp and the Raiders in 2006 training camp, but hasn't played in the regular season since 2003.

Because the Patriots run a bulk of plays with two tight ends, the team has preferred to activate three tight ends for games whenever possible. Daniel Graham, Watson, and rookie David Thomas are the top players on the depth chart, but Watson injured his left knee during last Sunday's loss to the Dolphins and is questionable for Sunday's game against Houston , giving him a 50-50 chance of playing.

Watson, who leads the team in catches (49) and receiving yards (643), wasn't present at the start of yesterday's practice. Graham acknowledged the team would be missing a threat without Watson.

"He's been a big key in our offense and our passing game this year," Graham said. "We have to depend on other guys to step up, get open, and catch the ball. We can't stop what we're doing because we lose a guy, we just need someone to step in and fill the shoes."

Thomas, a third-round pick from the University of Texas, would figure to see an expanded role. He has three catches for 52 yards on the season.

"He's learning this offense and it's not an easy offense to learn, but he's picked it up pretty well," Graham said.

The 6-foot-7-inch, 265-pound Santiago has 81 career receptions for 1,041 yards and nine touchdowns. He also has experience on special teams, which might have been a factor in the signing.

Why didn't it work out for receiver Doug Gabriel in New England?

Coach Bill Belichick said the team's system isn't a great fit for every receiver, and apparently Gabriel falls in that category.

"I think that's related to it," Belichick said. "I would say that we could say that about a lot of players that have been here, that are in the league and playing with other teams and doing better than they did here. I would say that's definitely relevant."

Gabriel, who had 25 catches while playing in 12 games with five starts, was released Tuesday and claimed by the Raiders yesterday. Belichick said he appreciated "how hard [Gabriel] worked and what he tried to do here, [but] it just didn't work out."

"You can never tell," said running back Kevin Faulk. "I'm not going to lie, the [philosophy] of this organization is different. Sometimes you want to try to figure out what they're thinking but it's not the best thing you can do."

The Patriots placed running back Patrick Pass on injured reserve because of an ailing hamstring, ending his season. He becomes the 12th player placed on injured reserve since the start of training camp.

A seven-year veteran, Pass had appeared in the past three games after being activated off the physically unable to perform list. He finished with six rushes for 21 yards and two catches for 24 yards.

The Patriots now have Corey Dillon, Faulk, Heath Evans, and Laurence Maroney at running back. Maroney remains questionable for the second straight week because of a back injury.

Pass also was a kickoff returner, and his absence could lead to increased opportunities for defensive backs Ellis Hobbs and Willie Andrews. Pass is scheduled to become an unrestricted free agent at season's end .

Comments from Dolphins defenders about studying Tom Brady's protection calls at the line of scrimmage remained a hot topic in South Florida yesterday. After speaking with some of his veterans, coach Nick Saban said it's a part of preparation that has been part of the Dolphins' repertoire for years, and he felt the team was being cast in an unflattering light.

Referring to some media reports on the issue, Saban said, "Now they've got us stealing stuff, buying stuff. It's unbelievable."

Defensive end Jason Taylor added, "I'm sure every team looks at the cadence from TV copies of the week before. We're not down here finding the cure for cancer or building new rockets to go to the moon."

Linebacker Zach Thomas felt the attention the story received took away from the team's victory.

"Everybody's thinking the only way we can beat the New England Patriots is if we steal their signals. There was no stealing signals," he said. "You watch tape. If I knew the signals, I wouldn't tell them. I'd be stupid. You need to slap me if I tell you I figured out their signals."

In a sign his rehabilitation has taken another step forward, safety Rodney Harrison was upgraded from out to doubtful on this week's injury report. Harrison suffered a broken scapula Nov. 5 and hasn't played since . . . Nose tackle Vince Wilfork, who left last Sunday's loss because of a right ankle injury, is listed as questionable. Wilfork wasn't present for the start of yesterday's practice . . . Nose tackle Mike Wright (questionable, shoulder), was another addition to the injury report . . . Patriots offensive linemen, who had been growing beards since the start of the season, sported a clean shaven look, which appeared to be a move designed to change their fortunes after a difficult performance in Miami . . . The Patriots re-signed offensive lineman Gene Mruczkowski, who begins his fourth stint with the team. He had been released last Saturday . . . Tight end Rod Trafford, who had spent time with the team in 2003 training camp, was signed to the practice squad. He has played in four career games, all with the Bills in 2004.

Amalie Benjamin of the Globe staff contributed to this report; Mike Reiss can be reached at mreiss@globe.com.