We've spent a lot of time detailing just how good Michigan State's defense has been this season, and anyone who had any doubt about it was silenced after the Spartans' wildly impressive performance in a 29-6 win over Michigan last Saturday.

Michigan State head coach Mark Dantonio has said this season's defense has a chance to rank as the greatest he's coached, which included the 2002 Ohio State national championship team on which he served as defensive coordinator. But Dantonio has also cautioned that the 2013 Spartans will be judged at the end of the year, not during it.

That's true, but it doesn't prevent us from taking a look at some of the crazy stats being put up by Pat Narduzzi's Spartan Dawg defense. Here are some of the national rankings for that unit, culled from both official NCAA stats and ESPN Stats & Info:

Total defense: No. 1

Rush defense: No. 1

Pass efficiency defense: No. 1

Scoring defense: No. 3

Yards per play: No. 1

Yards per rush: No. 1

Passing yards per game: No. 4

Passing yards per attempt: No. 1

First downs per game: No. 1

Third down conversion rate: No. 2

Plays gaining 10 yards or more: No. 1

Plays gaining 20 yards or more: No. 4 (tied)

Percent of plays gaining first down or TD: No. 1

Percent of zero or negative plays: No. 1

Total expected points added by team defense: No. 1

Win probability added by team defense: No. 2

So, yeah, it's hard to get much better than that. We also wondered how this Michigan State defense stacked up to some of the best in recent Big Ten history. We reviewed the official Big Ten defensive statistics, which detail the leaders in key categories since 1985, to find out:

Total defense

2013 Michigan State: 210.2 yards per game

That figure would be the lowest in the Big Ten since 1985 if it held for the entire season. Only three teams in that span have allowed less than 235 yards per game over a full season: 1997 Michigan (222.8), 1987 Michigan State (225.6) and 2007 Ohio State (233). The '02 Buckeyes gave up 320.9 yards per game.

Rush defense

2013 Michigan State: 43.4 yards per game

The Spartans' current number would tie the 2006 Michigan team for the lowest number since 1985. No other team in that span has held teams to under 60 rushing yards per game. Dantonio's 2002 Buckeyes allowed 77.7 rushing yards per game.

Pass efficiency defense

2013 Michigan State: 90.29 rating

The Spartans' current pace would be the best in the Big Ten since 2009 Iowa (90.0). Only four teams since 1985 have posted a 90 or lower pass efficiency defense rating, led by 1998 Michigan's 49.9.

Scoring defense

2013 Michigan State: 11.6 ppg

The last Big Ten team to hold opponents under 12 points per game for an entire season was Wisconsin in 1998 (11.9 ppg). The Spartans' current number would be the lowest in the league since the 1996 Ohio State defense yielded 10.9 ppg. The 1985 Michigan Wolverines gave up just 6.8 ppg, while the '97 Wolverines allowed only 9.5. The '02 Buckeyes surrendered 13.1 ppg.

Numbers can be twisted and turned in a lot of different ways. But however you want to look at this 2013 Michigan State defense, it's hard to deny that the unit is doing some historic things.