Over the course of their history, the Steelers have produced some of the best defenses that the NFL has ever seen, but this year's unit might top them all, at least statistically. 

Heading into Week 13, the Steelers defense leads the NFL in three key categories: They have the most sacks (41), the most takeaways (23) and they've also given up the fewest points (188). The reason that's notable is that since the AFL-NFL merger in 1970, no defense has ever finished the season as the leader in all three of those categories. For defenses, this is basically the triple crown. 

To give you an idea of just how difficult it is to lead the NFL in all of those three categories, just consider this: Only three teams, including the Steeles, have ever even made it to December while ranked first in each of those categories. The last team to do it was the 2017 Jaguars and they ended up riding their defense all the way to the AFC title game before losing to Tom Brady and the Patriots. However, the Jaguars didn't end up leading the NFL in any of those categories. The closest any team has come to leading in all three came with the 1985 Bears, the 2000 Ravens and the 2013 Seahawks, who all led the NFL in two of three categories. 

Those three aforementioned teams also have one other thing in common: They all won the Super Bowl and they did it in dominating fashion. The Seahawks beat the Broncos 43-8 while the Ravens topped the Giants 34-7. As for the Bears, they beat New England 46-10, which means those three defenses gave up an average of six points per game (The touchdown against the Ravens came on kickoff return, so we're not holding that against their defense). 

Here's how each of those defenses finished in each category:

1985 Bears: This is largely considered the greatest defense of all-time, but even the Bears didn't lead the NFL in all three categories. After the 1985 season ended, the Bears were ranked first in takeaways and they also gave up the fewest points in the NFL, but they didn't end the year as the overall sack leaders. Led by Richard Dent, who totaled an NFL-high 17 sacks, the Bears racked up a total of 64 sacks in 1985. However, that was only good for third as the Giants (68) and Raiders both finished with more (65). 

Result: Gave up the fewest points, first in takeaways, third in sacks. 

2000 Ravens: Like the 1985 Bears, the Ravens finished the season as the leader in two of these three metrics, but they couldn't quite finish off the sweep. Although the Ravens ranked first in takeaways while also giving up the fewest points, they didn't end the year with the overall sack lead. Back in 2000, if the Ravens struggled at one thing, it was sacking the opposing quarterback. Baltimore recorded just 35 sacks on the season, which ranked 22nd in the NFL and put them well behind the Saints, who led the league with 66. 

Result: Gave up the fewest points, first in takeaways, 22nd in sacks.

2013 Seahawks: When the "Legion of Boom" was in its prime, the Seahawks had one of the best defenses in the NFL. Not only did they give up the fewest points in 2013, but they also led the NFL in takeaways with 39. To put into perspective how dominant that was, only one other team in the NFL even had more than 31 that year. As for sacks, the Seahawks weren't even in the top-10 heading into Week 15, but they racked up eight over their final three games to finish with 44, which was good enough for eighth in the NFL, but well behind the Panthers, who had 60 on the season. 

Result: Gave up the fewest points, first in takeaways, tied for eighth in sacks.

2017 Jaguars: Although the Jaguars didn't finish the clean sweep, they did end up finishing in second in all three categories. In the sack department, the Jaguars finished with 55, which left them one behind the Steelers, who led the league with 56. The Steelers actually racked up six sacks in their regular season finale, which allowed them to steal the sack title from Jacksonville. Ironically enough, the Jaguars and Steelers ended up meeting in the playoffs that year and Jacksonville won a game where they sacked Ben Roethlisberger twice while giving up zero sacks. As for points allowed, the Jaguars surrendered 268 on the season, which finished second behind the Vikings, who only gave up 252 points. The Jaguars also had 33 takeaways on the year, which put them one behind the Ravens, who had 34. 

Result: Gave up the second-fewest points, second in takeaways, second in sacks.

As for the Steelers, it's not that crazy to think they could be the first team to pull off the defensive triple crown. They have 23 takeaways on the year, which leads the NFL by three. To lose this lead, the Steelers are going to have to slow down their pace or the second-place team (Tampa Bay) is going to have to pick things up. With the Buccaneers on a bye this week, the Steelers could actually extend their lead in the turnover department if they can force a few against Washington. 

On the points end, the Steelers have only surrendered 188 points on the season, which puts them comfortably ahead of the Dolphins (205), Ravens (214) and Rams (215). Of the Steelers remaining five opponents, three of them -- Cleveland, Cincinnati and Washington -- rank in the bottom half of the league in scoring. 

The Steelers also lead the NFL in sacks, but this could be the most difficult one to win. Through 12 weeks, the Steelers have 41 sacks, which is five more than anyone else, but the problem here is that they just lost Bud Dupree for the season. Dupree was second on the team in sacks with eight and he won't be easy to replace. That being said, the Bengals have surrendered the second-most sacks in the NFL and Washington has given up the third-most, so there are definitely a few games on their remaining schedule where the Steelers should be able to pad their stats. 

Basically, the Steelers are on the cusp of making history and it's not too crazy to think that the 2020 version of the Steel Curtain can pull it off.