Will the Jets activate QB Greg McElroy? Tim Tebow is still nursing cracked ribs. (US Presswire)

The standard protocol for most NFL teams is to keep three quarterbacks on their roster. On game day, usually just the starter and his backup are active because, with the ability to dress only 46 players, those spots are at a premium and no team wants to use a spot on a guy who won't play. However, injuries can change that. An injury to one of the top two guys will generally activate quarterback No. 3.

However, it's not always black and white as the Jets recently realized. Against Seattle in Week 10, QB Tim Tebow cracked his ribs. The injury wasn't discovered until after the following week's game against the Rams when his discomfort started to increase. With the Jets playing on a short turnaround on Thanksgiving, the team was faced with playing Tebow, or having him sit and activating third-string QB Greg McElroy. The Jets are also in the unique position of using Tebow not just on offense but using him as the personal protector on the punt team.

Believe it or not, broken ribs don't necessarily preclude a quarterback from playing, which was one of the reasons the Jets chose to keep Tebow active for the game on Thanksgiving night in the Jets' 49-19 loss to the Patriots. And he openly admitted that he strongly lobbied to play, citing how he played with a broken leg in high school. However, questions have arisen as to why the Jets would have kept Tebow active in that game, when, according to coach Rex Ryan, they were only going to use him in the event of "an emergency" and in spite of the fact that McElroy, the team's third-string QB, was healthy.

"I don’t know how many teams in this league go with three quarterbacks [in a game)," Ryan said.

On Monday following their Thanksgiving game, McElroy (who played once in college with broken ribs) said he had been informed about what was going on all week and was ready to go if needed, although with the short week of preparation, he took no reps in practice.

"It was a game-time decision last week," McElroy said. "And Tim wanted to give it a go in pre-game."

As for this week, McElroy continued in his usual role, running the scout team. On Friday, Ryan said he had not made a decision about Sunday and that it likely wouldn't be made until game time.

But, if necessary, McElroy can step in. "I feel comfortable," he said. "I feel like I know what [the coaches] want us to do. I feel like I have a good understanding."

McElroy, now in his second year out of the University of Alabama where he led the team to the BCS championship in 2010, missed his entire rookie season after being put on injured reserve following surgery on a dislocated thumb, which he injured during the last preseason game (against the Eagles) in 2011. He has yet to play in a regular season game.

But all of this raises another questions, what if there are only two active quarterbacks and both are injured? It happened to the Jets once in 2005. Playing the Jaguars at home, QB Chad Pennington left the game with a shoulder injury. Three plays later backup QB Jay Fiedler was knocked out, also with a shoulder injury. Third string QB Brooks Bollinger was inactive, so Pennington returned, but he was hampered for the remainder of the game. In cases like this or worse, most teams have what's known as an "emergency quarterback." Often, this is a player who played quarterback in high school or college.

So, who is the Jets' emergency quarterback? WR Jeremy Kerley who played quarterback in high school. Coach Rex Ryan was quick to point out with a wry chuckle that if it ever came to that, Kerley's role would likely be solely to hand the ball off.

Kerley, however, might have something else up his sleeve should the situation ever present itself. "I'm throwing it," he laughed.

Joking aside, the Jets are monitoring Tebow, and Ryan said he doesn't anticipate a change in his availability for Sunday against the Cardinals. That said, it's still not clear whether the Jets will make McElroy active as extra insurance.

Stay dialed in on the New York Jets by following correspondent Lisa Zimmerman on Twitter @CBSJets and@LisaZimmerman.