ALLEN PARK -- Matthew Stafford hasn't missed a start since 2010. That's 112 straight games, the third longest active QB streak in the league. Heck, it's the eighth longest ever.

The last two years, he's missed just nine of Detroit's 2,069 offensive snaps. That's 0.4 percent.

All of which begs a question: What exactly does a Matthew Stafford backup do anyway?

That's a relevant question these days, with Jake Rudock trying to fend off newcomer Matt Cassel for the No. 2 job in Detroit. Neither has been particularly good in camp. Rudock has been better in the preseason -- his 90.1 rating is a team high -- but he's done much of his damage against deep reserves.

Cassel has completed just 16 of his 27 passes for 123 yards. He's thrown a pick and fumbled. Just one of his seven series resulted in points, a touchdown run by Ameer Abdullah in the opener.

Then again, neither really figures to play much no matter who wins the job. So what exactly are the Lions looking for here?

The main thing is he has to be able to help Stafford with the tape.

"I can't watch every snap of every game a team has played for the last however many years," Stafford said. "There's just not enough time in the day, so being able to get a separate set of eyes on some tape and some ideas, maybe a guy has played against a guy in college or played against him two years ago in the pros or was on his team. All that stuff is information that is relevant and can help.

"Obviously early in the season, little bit less tape out there, but as you get later in the season maybe you find a game or two that you think a guy can dive through and maybe find something in."

That's where a guy like Cassel could have an edge. He has 13 years of service time in the league, four of which were accrued with Patricia and Bob Quinn in New England. He's played for nine offensive coordinators and faced an untold number of defensive coordinators and schemes. He's also logged 81 starts. That's a wealth of experience to lean on in meeting rooms.

By contrast, Rudock has only appeared in one game in his two years in Detroit. He's attempted five passes, one of which was a pick-six.

Then again, Rudock does have two years of experience with Stafford, and Stafford said he'd work well with either as his backup. Cassel probably has the edge heading into Friday's game against Tampa Bay, but the race remains open with just 11 days until cuts.

"I've kind of had all different kinds and been able to co-exist and play well with all kinds," Stafford said. "I think that's really not my decision to tell you the truth. But, we're just looking for guys that can help this team. That's every position, that's backup quarterback, that's wide receiver, running back, anybody on defense, it doesn't matter. We're all just in competition to try to be as good as we can be and help our team win.

"I'm not too worried about that. We've got two really capable guys behind me battling it out, so the chips will fall where they do on that one and we'll see."

Patricia will have a serious say in the decision, although it'll ultimately be Quinn's call to make. Patricia said the exhibitions matter, but everything else matters just as much in the club's evaluation of the QB race. It really comes down to who is the best fit for supporting Stafford, rather than just who has the best preseason.

"We're certainly going to want to see their on-field performance, first and foremost," Patricia said. "But their preparation, their professionalism, how they attack the day, the daily game plan, the weekly game plan, how they prepare themselves, is definitely all part of the evaluation. It's really like that with every position, (but) I would say there's a lot more emphasis put on the quarterback."