Think preseason games are meaningless time-wasters?

Ponder this: Over the next week, Marcus Thigpen could become the Dolphins’ top kick returner, receiver Roberto Wallace could lock down a starting job, and Pat Devlin could prove he’s ready to be the Dolphins’ emergency quarterback.

Or, any (or all three) could be off the team altogether.

That’s what’s on the line for Thigpen, Wallace, Devlin and some two dozen other bubble players when the Dolphins host the Falcons in Friday’s exhibition game.

“There’s a lot of jobs up for stake,” said Dolphins coach Joe Philbin. “It’s getting down to the time where it’s going to be serious business for a lot of guys. So I think there’s quite a few jobs open.”

They call the third preseason game a team’s final dress rehearsal, since starters traditionally play into the second half.

But for at least 13 guys, Friday night will be their swan song in a Dolphins uniform. The first round of cuts is Monday. Miami’s roster, which currently has 88 names, needs to get down to 75 by then.

And that’s just a prelude to Aug. 31, when the final 53-man squad must be named.

Since camp began four weeks ago, Philbin and his staff have drawn up mock opening day rosters at least four times, moving players on and off the board based on performance.

“It’s kind of fun,” Philbin said this week.

Not if you’re a guy like Austin Spitler. With Karlos Dansby likely out of the Falcons game with a pesky knee injury, Spitler is in line to start at middle linebacker. If he plays well, he’s a good bet to make the 53.

If not, he could be a numbers-game casualty. As in: Do the Dolphins keep six linebackers or six receivers? Four running backs or nine offensive linemen? One fullback or none at all?

They can’t have them all.

“The receiving battle has been intense from OTAs,” said Marlon Moore, the third-year wideout who appears to be on the right side of the bubble. “There’s no lack of talent in this receiving corps. Everybody deserves to be on that field.”

Devlin’s performance should be particularly telling. The bosses clearly think well of him — tight ends coach Dan Campbell said on Hard Knocks that Devlin reminds him of a young Tony Romo. But well enough to jettison David Garrard?

Such a move would have been unthinkable just three weeks ago. But with Ryan Tannehill locked in as the opening day starter and Matt Moore a good locker-room presence, the Dolphins could save some money by cutting Garrard, if they think Devlin is ready.

That’s why we have both triggermen firmly on the bubble in our unofficial depth chart.

All of these projections are based on each player being healthy at or near the start of the season (which is no safe bet, considering Brian Hartline’s camp-long calf injury).

Also, there are financial (not to mention face-saving) factors that could supersede actual performance on the field (see: Michael Egnew, the underperforming third-round pick who will likely squeak through on investment alone).

With that in mind, here’s our working list of who’s in, who’s out, and who has work to do:

Locks (26)

QB Ryan Tannehill; WRs Davone Bess, Brian Hartline, Legedu Naanee; RB Reggie Bush; OL Artis Hicks, Richie Incognito, Jake Long, Jonathan Martin, Mike Pouncey; TE Anthony Fasano; DEs Jared Odrick, Cameron Wake; DTs Paul Soliai, Randy Starks; LBs Kevin Burnett, Karlos Dansby, Koa Misi; DBs Chris Clemons, Vontae Davis, Reshad Jones, Richard Marshall, Sean Smith; K Dan Carpenter; P Brandon Fields; LS John Denney.