The optimist will call it a day of comebacks. Detroit, San Francisco, the Giants and Cincinnati stormed back from double-digit deficits to win on Sunday.

The pessimist will call it a day of collapses. Dallas, Philadelphia, Arizona and Buffalo choked.

The realist will ignore all of that and call it a day of potentially massive injuries. Fans in Houston, Pittsburgh and New England are nervously awaiting updates on Andre Johnson (right hamstring), Ben Roethlisberger (left foot) and Jerod Mayo (left knee).

We’ll try to cover all of those bases in the week ahead. But now, 27 thoughts from the fourth Sunday of the NFL season…

1. The latest in “Are you serious?”: The Eagles are 1-3, the Falcons probably should be 1-3, the 49ers and Titans are 3-1 and the Steelers are tied for last place in the AFC North. Oh, and of course… the Lions are 4-0. Love this league.

2. In Baltimore, an early candidate for “Worst offensive game of the year.” Thirty-five points from defenses and special teams and 16 from offenses? Just sickening. And I can appreciate great defense, but this was more about putrid offense than fantastic D.

3. The Ravens have scored at least 34 points in three of their four games. And sooo much of it has to do with a defense that has forced 14 turnovers. That Week 2 loss to Tennessee was a blip. Joe Flacco doesn’t scare me, but he doesn’t have to.

4. And it turns out you can’t avoid missing a beat without an All-Pro center. The Jets are now 0-2 without Nick Mangold in the lineup. They might have lost to the Raiders regardless, but Mangold’s absence was toxic for New York against Baltimore. Mark Sanchez’s 11-completion, four-turnover performance was comical Sunday night, and he once again had no support from his running game.

5. Defensive coordinator career suicide: Lining up Terence Newman one-on-one with Calvin Johnson inside the red zone in a crucial situation. Children without electricity in Uganda knew Johnson was going to score on this play. Rob Ryan didn’t, apparently.

6. The 49ers are an overtime loss to Dallas removed from a 4-0 record. Yet I still think San Fran is sort of a phony 3-1. San Fran needed the Ted Ginn Week 1 miracle to get past Arizona, barely survived in Cincinnati and then edged the broken Eagles thanks to two missed gimme field goals from Alex Henery. They could easily be 4-0. They could easily be 0-4.

7. You don’t always have to run to win in this league, but it can help immensely, especially if your offensive line blows. Kudos to Mike Martz for waking up and finding ways to use Matt Forte and Marion Barber, who combined for 232 yards on 30 carries in Chicago’s 34-29 victory over Carolina. Surprise, surprise: Jay Cutler was sacked just once as the Bears’ pass-run ratio took a 180-degree turn.

8. And considering that they trailed for much of the day, the Panthers didn’t do a bad job working DeAngelo Williams and Jonathan Stewart into the offensive flow in Chicago. Can’t sneeze at 29 points in a tough road game for a young offense led by a rookie quarterback. Sentences rarely written for 300: Carolina and Chicago both have a lot to be happy about.

9. The Bills can’t panic. At least the first loss is out of the way. It doesn’t look good, but young teams learn with losses like those. The Bengals have been hanging with everyone thus far, and it’s not easy to win on the road after back-to-back emotional victories. Buffalo didn’t do anything horribly Sunday, and it once again did a great job protecting Ryan Fitzpatrick, who was sacked just once. They also had two takeaways while not committing any turnovers on offense. Philly and the Giants are on deck — they can’t dwell on a tough-luck road loss.

10. Pass protection isn’t Pittsburgh’s only problem. What’s up with the run defense? Houston has a great running game, but Arian Foster went nuts fresh off an injury. Despite having Aaron Smith back this year, the Steelers have plummeted against the run. Smith and James Harrison have been totally off their games. Somehow, a defense that surrendered just 3.0 yards per carry in 2010 has given up 4.8 yards per carry in 2011. That’s why they’re 2-2 and in serious trouble in the AFC North.

11. It’s a Pennsylvania thing. Notice that neither team from the Keystone state can stop the run or protect the passer?

12. Aaron Rodgers has emerged as the clear MVP frontrunner. His absurd 2010 playoff performance has carried over into 2011. Rodgers lit up the Broncos for 49 points Sunday, becoming the first player in NFL history with at least 400 passing yards, four passing touchdowns and two rushing touchdowns in a game. His 124.6 passer rating is towering over his peers, and he’s on pace to finish 2011 with a better touchdown-to-interception ratio (48-to-8) than Tom Brady had in 2010. At 27, he might officially be the league’s unofficial best quarterback. And it’s now safe to predict that he’ll end up with a larger legacy than his predecessor, Mr. Brett Favre.

13. And Brady might not be the top candidate on his own team. Um, Wes Welker is carrying the Pats right now. Right when many figured he’d never put up 2009-type numbers again, the 30-year-old has re-emerged as the game’s most consistently effective receiver in 2011. Four games in, Welker’s on pace to catch 160 passes for 2,464 yards and 20 touchdowns.

14. Sooo it’s not just about the tight ends in New England? Aaron Hernandez was out. Rob Gronkowski had one catch for 15 yards. The Patriots scored 31 points.

15. The league’s top two teams hail from the NFC North. At least on paper. And they’re doing it in very different ways. The Packers are blowing teams out and the Lions are comeback kids. In fact, they’re the comeback kids…

16. I suppose the loss of Ray Edwards isn’t affecting Jared Allen. Six and a half sacks out of the gate, putting him and Jason Babin (seven) on pace to break Michael Strahan’s single-season record (22.5). Allen’s start has been the only real bright spot for Minnesota. While I don’t think Babin will keep it up, I’m looking forward to an Allen-DeMarcus Ware battle throughout the 2011 campaign.

17. That revamped Texans defense is holding up. Ben Roethlisberger’s been off his game and may have been bothered by an injury, and Rashard Mendenhall was hurt, too, for Pittsburgh. But holding the Steelers to 10 points is one hell of a feat for a defense that’s historically bad, particularly against the pass in 2010. They weren’t as bad as the numbers indicated last week in New Orleans, and they held up and made some big plays in a win over the Steelers. Wade Phillips’ guys were getting good pressure. This game wouldn’t have been close had a pick six and a blocked punt return not been called back.

18. Proof that a star running back isn’t enough in this era: Jacksonville has scored 39 points this season. Five teams have scored more than that in single games thus far.

19. The Falcons can thank Pete Carroll. Had Carroll managed the clock better on that final drive, Seattle wouldn’t have been forced to settle for a 61-yard field goal attempt with 13 whole seconds on the clock. If you’re going to lose a one-score game that goes down to the wire, you should never hand it back to your opponent with a timeout in your back pocket and time on the clock.

20. Will the Bills pay their own talent? The fan base has bitched and whined over the franchise’s lack of aggressiveness in free agency for years, but now Buffalo has a group of talented borderline-stars on its own roster. But Ryan Fitzpatrick and Stevie Johnson are in contract years, and ProFootballTalk reports that talks between Johnson and the team broke off prior to the season, leaving the Bills in a sticky situation. If they let either guy go after a breakout season, the fans might take their rage to a whole new level.

21. Darrelle Revis. Nnamdi Asomugha. Asante Samuel. Troy Polamalu. Devin McCourty. Just listing a few star defensive backs who, at the quarter pole, have fewer interceptions than 325-pound Patriots defensive lineman Vince Wilfork.

22. Beanie Wells is averaging 107 rushing yards per start. Is it a new era in Arizona?

23. No reason Tim Tebow shouldn’t start in Denver. The Broncos suck either way, and at least that way they’d appease the fans, who do pay these guys’ salaries.

24. No reason Christian Ponder shouldn’t start in Minnesota. The Vikings suck either way, and sucking more would only help increase their chances of landing Andrew Luck. Plus, how are they supposed to know if they want Luck if they haven’t had a good look at Ponder?

25. Tony Sparano won’t be fired this week. But if he were to get canned, it wouldn’t have much to do with the loss to San Diego. It would have everything to do, instead, with the first three weeks and the fact that Miami has two weeks off now. Still, it won’t happen. It should, but it won’t.

26. Slickest coaching decision of the week: Jim Harbaugh kept his young, travelling team in Ohio for the entire week after last week’s win in Cincinnati. Less time in the air, more time bonding. Back-to-back road wins have the Niners cruising above their heads at 3-1.

27. I’m starting to wonder if Joe Buck is really, really bored. Like, does the guy still enjoy sports at all?