Mike Zimmer woke up in a good mood Saturday. How does one know that? The Vikings coach gave 31 players the day off in the preseason opener, even guys who have limited NFL experience.

Basically, every front-line or semi-meaningful player sat out vs. the Denver Broncos, and the result left Zimmer fuming: a 33-6 loss with the aesthetics of a 20-car pileup.

Those wondering what kind of reception Kirk Cousins would receive from fans inside U.S. Bank Stadium will have to wait a while longer for that answer. Same thing for those curious/anxious/panicked about the reconfigured offensive line and whether the weak link will keep that title again this season.

On cue, the first points allowed by the Vikings came in the first quarter via a safety awarded to the Broncos on a holding penalty by an offensive lineman in the end zone.

That ought to calm the masses.

None of the five linemen listed as starters on the first depth chart played in the game. Of those five players, only one — right tackle Brian O'Neill — comes without any concerns or unknowns. O'Neill is ascending to star status.

After him, nothing but questions of varying degree.

That doesn't guarantee doomsday necessarily, just that we really have no idea about that group and being skeptical that things will be better is entirely justified.

The post-draft opinion was that Rick Spielman invested the necessary capital to improve the offensive line by taking tackle Christian Darrisaw in the first round and guard Wyatt Davis in the third round.

Plug and play, right?

Those of us who anticipated the two rookie linemen starting in the season opener were probably being naïve, even if the duo has a low bar to clear to be viewed as upgrades. Assuming a seamless transition to starting roles ignores the reality that Zimmer doesn't just hand jobs to rookies based on their college résumé and draft status.

Darrisaw isn't close to being ready physically after having a second surgery on his groin this past week, and Davis is third on the depth chart at right guard, somehow behind Dakota Dozier.

The Vikings moved on from left tackle Riley Reiff, who was their second-best lineman last season, and seem content replacing him with Rashod Hill, a backup primarily throughout his career. This is a big gamble, not knowing if Hill can handle premier pass rushers for a full season.

Darrisaw should take over that job at some point, but his development will be a slow process because of how much practice time he's already missed. Making sure he is 100% healthy and not letting his injury linger becomes the primary focus.

The line's interior is of equal (or greater) concern. That area consistently caved under pressure last season, causing Cousins to duck for cover.

Left guard Ezra Cleveland showed some promise as a rookie, but he is not in the category of established yet. This is a make-or-break season for center Garrett Bradbury, a first-round pick who has been a liability in pass protection. And converted tackle Oli Udoh seems to have won the right guard spot.

So, yeah.

Udoh's résumé is thin, with only seven career games played, but Zimmer allowed him to sit out the preseason opener, a telltale sign that he's the presumed starter.

Dozier might have played himself out of a roster spot by getting a holding penalty in the end zone for a safety and then a false start penalty later in the first quarter.

Davis replaced Dozier in the second quarter and immediately got shoved into the backfield by Vikings castoff Shamar Stephen, which added some insult to that rookie moment.

So the never-ending story line lingers into another season. With the collection of skill players surrounding Cousins, the Vikings should have a top-10 scoring offense this season after finishing 11th in the league last season. Anything less than that will be a disappointment.

The difference between a good offense and a high-scoring one primarily rests with one area, and the same old questions haven't gone away.