I'm currently working on my 21st Super Bowl preview. That should run in the middle of next week, a few days before Super Bowl Sunday, but this means waiting more than a week before unveiling all the stat tidbits that get you ready for the big matchup. It was one thing when I was the only person on the Internet doing a Super Bowl preview packed with advanced stats. Now you can get all kinds of advanced metrics from all kinds of websites. So I now produce a pre-preview each year to get you ready for the Super Bowl hype. This is just me emptying my notebook witha few of the cool stat splits that I've found while preparing our Super Bowl LVIII preview. These stats will all appear again when we get to the actual Super Bowl preview next week.

1) The first thing you may notice when comparing regular DVOA to weighted DVOA is that the Kansas City Chiefs defense has improved over the course of the season while the San Francisco 49ers defense has declined. This is in large part an artifact of teams sitting starters in Week 18. The Chiefs defense played very well against Easton Stick while the 49ers defense did not play well against Carson Wentz. Here are both defenses split at midseason but with Week 18 removed. This is a particularly apt split because 49ers safety Talanoa Hufanga was injured early in Week 11 against Tampa Bay.

KC/SF Defensive DVOA by Week, 2023
WeeksTeamDVOARkPassRkRunRk
Wk 1-10KC-8.5%7-12.1%3-3.1%24
Wk 1-10SF-7.2%8-8.1%5-5.4%20
Wk 11-17, 19-21KC-8.7%8-15.5%30.8%25
Wk 11-17, 19-21SF-10.3%6-12.7%6-6.5%19

This table also makes clear one of the major storylines of Super Bowl LVIII, which is that both defenses are susceptible to the run against two teams with strong running backs. It's a colossal advantage for the 49ers in particular. The 49ers were No. 1 rushing on first down and No. 2 rushing on second down. The Chiefs were 26th and 25th on defense, respectively. Things are closer on third downs, where the 49ers were 15th and the Chiefs defense was 18th.

2) The 49ers running game averaged 7.2 yards per carry when opponents had only 6 in the box. The Chiefs put only 6 in the box 38% of the time during the regular season, usually when they were tied or leading by a small amount. Do not do that!

3) I introduced a new cornerback coverage DVOA this year, which I've written about here a few times and on Twitter a lot. The cornerback coverage DVOA is based on all coverage snaps, so it's tracking not only giving up completions but giving up big plays as well as preventing targets in the first place.

It's notable that none of the 49ers cornerbacks stand out as particularly better or worse in the cornerback coverage DVOA. They all are a little bit above average. They were all better in the second half of the season.

L'Jarius Sneed at -23% DVOA is the best KC corner by the new cornerback coverage DVOA. Trent McDuffie comes out as surprisingly average, very different from his All-Pro reputation. Joshua Williams and Jaylen Watson are very slightly below average. Just like the 49ers cornerbacks, the Chiefs cornerbacks all come out as better in the second half of the season.

4) The 49ers are the No. 1 defense against passes up the middle. Fred Warner and Dre Greenlaw, of course. Mahomes was average on middle passes during the regular season. But he's been fantastic on middle passes in the postseason: 10-for-17, 11.5 yards per pass, almost all first downs.

5) The Chiefs defense was only 19th in DVOA against wide receivers in the slot or lined up tight during the regular season. They were sixth against wide receivers lined up wide.

6) The Chiefs offense struggled on first downs this season (17th in DVOA) and they only have 13.2% DVOA there in the playoffs (seventh out of 14 playoff teams). 49ers defense was seventh in the league on first downs during the regular season. The Chiefs have been much better on second downs and third downs during the playoffs.

7) The 49ers have a better DVOA against 11 personnel (-11%) because of turnovers, but allow fewer yards per play (4.6 vs. 5.2) to 12 personnel.

8) The Chiefs have a clear advantage on special teams, particularly on field goals and punts (with a good punter compared to poor punt returns from the 49ers).

I'll have a lot more to say in my official Super Bowl preview coming next week.