What did we learn from preseason? Very little

The Vikings held their first training-camp practice 45 days ago in Mankato amid the highest expectations of Brad Childress' three-year tenure as head coach. Free-agent newcomers Bernard Berrian, Madieu Williams and Thomas Tapeh, along with the team's marquee acquisition, Jared Allen, all were on the field.

Since that time the Vikings have held numerous practices that were open to the public and played 240 minutes of preseason football. But as they prepare to open the regular season Monday night in Green Bay, the reality is that the amount of useful information gleaned from having watched this team for a month-plus remains, at best, limited.

Many of the reasons for this have been beyond the Vikings' control, but nonetheless it's not exactly the way Childress likely envisioned spending his preparation time for the 2008 season.

Williams, signed as a free agent from Cincinnati, was out for six weeks early in camp because of a neck injury that is expected to keep him out for at least the first three games. Rookie Tyrell Johnson, a second-round pick last April, is expected to hold down the starting safety role opposite Darren Sharper for the short term.

But it is the offense about which we know the least.

Expressing any real concern about Adrian Peterson's 2.6-yard rushing average on 20 preseason carries seems a waste of one's time, given the other issues facing this unit.

Tarvaris Jackson, entering his second season as the starting quarterback and with much to prove, looked as if he had made significant strides during the preseason. He completed 15 of 22 passes for 200 yards with two touchdowns, no interceptions and an impressive 127.1 passer rating in four-plus series.

And then he suffered a sprained medial collateral ligament in his right knee that limited him in practice and kept him out of the final two exhibitions. This might not have been a concern with a veteran but for Jackson, any game action remains valuable.

Jackson and wide receiver Berrian, who got $16 million in guarantees to leave the Bears and sign as a free agent with the Vikings, spent time in the offseason working on their timing.

But they will enter Monday's game having played a grand total of three preseason series together, all in the opening game against Seattle. And this isn't all because of Jackson's injury.

Berrian was hobbled because of a groin strain when camp opened and missed the last three preseason games in part because of a toe problem that bothered him last year.

Berrian still played in all 16 games in 2007 and had a career-high 71 receptions to go along with five touchdowns. But Berrian is getting big bucks because his ability to stretch the field should keep defenses honest and open up things for Peterson. If he continues to be bothered by a problem affecting his speed, the field shrinks and opponents go back to crowding the line of scrimmage to stop Peterson.

Then there is left tackle Bryant McKinnie's suspension for the first four games of the season for violating the NFL's personal conduct policy. The Vikings could not have been shocked by the ruling from no-nonsense Commissioner Roger Goodell, but it might be the development with the greatest ripple effect.

At least Jackson and Berrian should be on the field Monday night.

McKinnie's streak of 89 consecutive starts, the most of any current Vikings player, will come to an end. Instead, Jackson's blind side will be protected by veteran Artis Hicks, who has made only four of his 49 career regular-season starts at left tackle. That means Hicks stands to make as many starts at left tackle by the end of this month as he has in his career.

When McKinnie does return, one-quarter of the Vikings' season will be completed. At least by that point, good or bad, we'll have some answers.

Judd Zulgad • jzulgad@startribune.com