Michael Boley and new guy Keith Rivers are best of the linebackers

Michael Boley wasn't on the field for every snap against the Cowboys on Wednesday night because of the hamstring injury that had been bothering him since the start of training camp. His replacement in the starting lineup, Keith Rivers, did not play the entire game, either. He, too, had a hamstring injury that popped up during the game.

If only the Giants could take the healthy leg from each of them and put them together into a sort of Franken-linebacker. "Yeah," Rivers chuckled, "we'd be one healthy, good player."

Eventually, they probably will be two healthy, good players. In fact, they'll probably wind up being the Giants' two best linebackers.

Boley was the best last year and returns as the brain center of the defense. Rivers, who hadn't played since 2010, showed flashes Wednesday of why he was the ninth overall pick by Cincinnati in the 2008 draft.

The problem is, they play the same position. There's room for movement, of course, and one could always move inside or over to the strong side in certain schemes. But if the Giants are adamant about putting their best 11 players on the field, as they often say they are, Boley and Rivers will have to be included in that group.

Something has to give.

Not right now, of course. Not while they still are hampered by sore hamstrings and need each other to be whole.

"There's plenty of room for plenty of people," coach Tom Coughlin said. "We'd like to have as many linebackers [as possible]."

Rivers said he's no longer trying to figure out where he fits in the defense in terms of starting and roles. He's just decided to play when he's told to and stand by and help when he's not.

"I've given up on trying to think about that," he said. "If I do that, then I'm worried about the wrong things."

Boley also deflected questions about getting his starting job back next week. His expectations, he said, have nothing to do with starting. "I expect to do whatever they need me to do," he said.

On Wednesday, both were able to handle that. Boley had a big interception that he returned 51 yards to the Dallas 2-yard line to set up a field goal. Rivers was second on the team with seven tackles, including an impressive one in which he fended off tight end Jason Witten with his surgically repaired right arm and made a one-armed tackle of DeMarco Murray with his left.

There were plays Rivers left on the field, though. He mistimed his blitz on Tony Romo's second touchdown pass to Kevin Ogletree, charging the line too soon and allowing the Cowboys to decipher the coverage and reconfigure their play. Earlier, Rivers blitzed Romo and was unblocked, but the quarterback spun out of the pocket and was able to get the pass off (which was almost intercepted by Corey Webster).

"You know he's going to spin that way and sometimes you get a little anxious," Rivers said of that play. "You kind of get away from your technique and get into survival mode."

Overall, Rivers played well for someone who missed all of last season on injured reserve. The Giants traded a fifth-round pick to the Bengals for Rivers, and through one game, it's certainly been worth the expense.

"I like what he did," Boley said of Rivers' play. "He stepped up and played physical. Was making plays at the line, behind the line. I like what he did."

Rivers admitted to being nervous for his regular-season debut with the Giants, but he calmed down by reminding himself that he'd been in plenty of NFL games before. He'd been with the team since the spring, through OTAs and minicamps, through training camp and preseason games. But he said it wasn't until Wednesday that he felt as though he really was a Giant. "Now it's official," he said. "It's in the books."

Where he goes from here, what position he plays and how much he's on the field, well, that part of the book has yet to be written.