What are the chances for these NFL teams to go undefeated?

We are halfway through the football season and we still have three undefeated teams in the NFL. The Patriots, Bengals, and Panthers are all 8-0. This is the first time in history three teams have gone unbeaten so long.

The question now is simply: How much longer can they go? According to our numbers, don't expect much. We'll be lucky to get one undefeated team — and look for a couple of these teams to drop out of the unbeaten ranks soon.

We used analytics numbers from Ed Feng, founder of sports site The Power Rank. Here's what we got:

For all three teams, we looked at their expected winning probability the rest of the season — eight games for each team. We multiply those probabilities to get a cumulative likelihood of making it all the way through the regular season. Conicdentally, the three leaders don't play each other in the regular season, so it's possible they could all end up undefeated.

For example, if a team had a 60 percent chance of winning one game, and a 55 percent chance of winning the next game, then it would have a 0.6 x 0.55 = 33 percent chance of winning both games. All three teams have a good chance of winning this week, but after that the numbers drop off fast.

The Patriots lead the way, with a 6 percent chance of getting to 16-0. They are favored in every game except a road trip to Denver in a couple of weeks. The Pats went 16-0 in 2007 but then lost in the Super Bowl.

The Bengals have a 4.2 percent chance of going undefeated. Their two biggest threats are road games at Arizona and (sound familiar?) at Denver — in each case Feng's analytics give the Bengals only a 45 percent chance of winning. Cincinnati's easiest win on the schedule should be home versus Houston — 85 percent chance to win.

And the Panthers have a 4.4 percent chance of winning the rest of the way. The interesting thing about the Panthers is they are favored in every one of their upcoming games, but in no game do they have over an 80 percent chance of winning. Contrast that with the Patriots and Bengals, who are almost always heavy favorites in their games.

If you don't like these numbers, you can also refer to the probabilities from ESPN's Football Power Index (FPI) projections. If we look at that group's latest odds, the perfect season probabilities are very similar to Feng's.

The FPI numbers are actually more bullish on the Patriots, giving them a 6.7 percent chance of making it to 16-0. But the FPI doesn't expect as much from the Panthers and Bengals — each of them are get just over 2 percent chances of going undefeated. As you can see in general though, the odds for each team making it all the way are in the low single-digits, no matter which projection system you use.

Of course these are just a guide for what to expect. If any (or more) of these teams go undefeated, it's not because the numbers are wrong — it's because what they did is so astonishing.