Last week, the NFL changed the rules regarding point after touchdown tries. While two-point conversion tries will still be attempted from the 2-yard line, extra point kicks will now be attempted from the 15-yard line rather than the two, turning the try into the equivalent of a 32-yard field goal attempt rather than a 19-yarder.

Broncos coach Gary Kubiak told ESPN.com that he thinks post-TD play-calling "will change a great deal," now that the extra point has been moved back, and indicated that the team is looking into the possibility of employing a two-point specialist in order to give themselves a leg up on those tries. The idea of having a two-point specialist is also something that has been floated as a reason the Philadelphia Eagles signed Tim Tebow.

But how much could a two-point specialist actually be worth? Let's take a look at some numbers.

Kickers had been making extra points at a rate of 98.7 percent since 1998 (as far back as the game-play database at Pro-Football-Reference goes), and in the last five years that number jumped had up to 99.3 percent. Since extra points are worth one point, you would expect each individual try to be worth 0.987 points since 1998, and 0.993 points over the last five years. That's basically an automatic point, but not quite.

Now that the try is moving back to the 15-yard line, the expected point value changes accordingly. Since 1998, kickers have made field goals from the 15-yard line at a 90.0 percent rate, which would yield 0.900 expected points on each kick. Narrow it down to the last five years, though, and the rate jumped to 94.1 percent, yielding 0.941 expected points.

Meanwhile, two-point conversion attempts have been successful 47.9 percent of the time since 1998, and exactly 50.0 percent of the time over the last five years. Here's a look at the expected point value of each in chart form.

Expected value
Time Period Extra Point 15-Yard FG 2PT Attempt
Since 1998
 0.987 0.900 0.958
Last 5 Years
 0.993 0.941 1.000

Using the last five years as a baseline for future success, two-point attempts now go from being worth 0.007 more points than an extra point to 0.059 more points due to the change in rules.

This isn't exact, obviously, but it's close. Not all field goal tries from the 15-yard line are equal (wind and other weather conditions could have an effect, for example), and kickers should get even more accurate from that range as they attempt more and more kicks from that distance over the next few years, so the expected value gap could close.

But let's say for the sake of argument that the 94.1 percent success rate from the 15 holds true for next season. How much would it be worth over the course of a season to have a two-point specialist that guarantees success on every try? Let's do some calculating again.

The average team scored 40.4 touchdowns last season. Using a 94.1 percent success rate on extra point tries, that would yield 38.0 points on those tries by the end of the year. If you nailed every two-point conversion, that brings 80.8 points, an increase of 42.8 points per year.

How much is that worth in terms of wins? Let's use the league average team, which scored 361.4 points last season, to show this again. You'd expect a team that scored exactly as many points as it allowed to have a 0.500 (8-8) record, using Pythagorean Winning Percentage (basically, the idea behind the concept is that point margin is a better predictor of future wins and losses than actual wins and losses).

Adding 42.8 points to that total brings us to 404.2 points, and using the same win expectancy formula, you'd get a 0.554 winning percentage, or the equivalent of 8.89 wins. Considering 0.89 wins could often be the difference between making and not making the playoffs, that would appear to be well worth it.

Of course, that 0.89 win total assumes two things: 1. A steady 94.1 percent conversion rate on field goals from the 15-yard line; and 2. Success on every single two-point try. Let's go to another chart to show how many wins would be added at a few different conversion rates, assuming field goals from the 15-yard line hold at a 94.1 percent clip.

Wins Added
Two Point Conversions 50% 60% 75% 90% 100%
Points Added
 2.4 10.5 22.6 34.7 42.8
Wins Added 0.04 0.23 0.48 0.73 0.88

Given that NFL coaches are generally risk-averse, we shouldn't expect to see many -- if any -- teams go for two on every touchdown, but some (like, say, Chip Kelly) will undoubtedly start doing so more often. Obviously the expected payoff for doing so grows as you become more successful with two-point tries, but there does appear to be a point where employing a specialist to raise your conversion rate could be more "worth it" than one might initially think.

UPDATE 11:53 a.m. Eastern

According to research done by ESPN.com's Kevin Seifert, field goals from between 30 and 35 yards away from the middle of the field have been made 97.6 percent of the time in the last two seasons. This is an important note because kickers will be able to place the ball in the middle of the field on extra point tries. Using that rate, we've again calculated the expected points and wins added at each two-point conversion success rate, which you can find in the table below.

Wins Added
Two Point Conversions 50% 60% 75% 90% 100%
Points Added
 0.97 9.05 21.17 33.29 41.37
Wins Added 0.02 0.20 0.45 0.70 0.86

Gary Kubiak may bring in a two-point specialist. (Getty Images)