I don't remember where or when, but at some point I saw a T-shirt that pointed out the half-full or half-empty glass expression for the amount of liquid doesn't account for the air in the container.

The analogy is often used for optimistic (half-full) or pessimistic (half-empty) perspectives.

As training camp approaches for the Vikings and 31 other NFL teams, it's possible to have both viewpoints, which was exemplified recently by The Athletic's Chad Graff and Arif Hasan.

The duo tag-teamed a season-preview series that included a story on concerns for the Vikings in 2022 and one that provided reasons to be optimistic.

In The Athletic's piece about concerns, Graff wrote:

Specifically, though, it's the defense that concerns me. The secondary has gotten a lot of talk because of the issues there, but that ignores the fact that the Vikings had one of the worst run defenses in the league a year ago. They're now switching to a defensive scheme that invites teams to run on them, potentially opening the door further for opposing rushing attacks.

Hasan replied:

If the Vikings are successful in baiting opponents into running the ball instead of throwing it, I consider that a win. So if they end up with a high-level passing defense at the cost of a mediocre run defense, that's fine to me. Their pass defense has always been better than their run defense, though last year was an outlier in that their run defense was substantially worse than the pass defense.

That weakness against the run mattered, but it mattered less than problems like situational passing defense in the final minutes, turnovers from the offense and special teams mishaps.

In The Athletic's reasons for optimism, Graff cited the addition of new, first-year Head Coach Kevin O'Connell and what the former NFL QB and offensive coordinator will mean to Minnesota's offense.

Though the Vikings will be more pass-happy than in recent years, I expect Dalvin Cook to play a massive role and for O'Connell to mesh [Rams Head Coach Sean] McVay's scheme with one that better utilizes the heavy formations the Vikings roster favors.

Perhaps I'm giving too much credit to a coach before Week 1, but I've been impressed by O'Connell and the way he has begun installing his scheme during practices. So when looking for reasons to be optimistic, I'm starting there.

Hasan said the offensive position group that he is highest on is receiver

Honestly, it's impossible to avoid the wide receiver position. It's easy to overrate the corps surrounding [Justin] Jefferson, but it's hard to overrate Jefferson himself; he's on track to earn consideration as the best receiver in the NFL. But even if we grant the worst-case scenario — say, that Jefferson is closer to eighth than first or that [Adam] Thielen is at the back end of his career — the Vikings still have an ascendant [K.J.] Osborn as well as exciting young players in Ihmir Smith-Marsette and Jalen Nailor.

'Big' question facing Vikings

Sports Illustrated's Will Ragatz is participating in a roundtable discussion of previews with other Fan Nation writers in the NFC North.

The group recently identified a "big remaining question" for each team.

Ragatz combined two position groups into one question, asking "Will the offensive line and secondary be good enough?"

As currently constructed, the Vikings have one key area on each side of the ball that's a relative unknown heading into the season.

Ragatz wrote the Vikings offensive line "is a potential weakness that could hold back an otherwise talented attack."

He believes the Vikings tackle situation is "actually quite promising" because of Brian O'Neill and Christian Darrisaw, but he noted the interior "remains a concern."

Defensively, the front seven looks stout. But this is a passing-driven league, so the Vikings secondary might make or break their defensive performance as a whole. It's a unit relying on two of the oldest players on the roster — possible Hall of Famers Harrison Smith and Patrick Peterson — to play at a high level. In addition to those two, the Vikings will be counting on three of the youngest players on the roster, including two rookies, to provide quality play. That mix of post- and pre-prime talent could work well — or it could be a bit of a mess.