Vikings Insider: After preseason-opening loss, team receives homework assignment

One preseason game down, three to go.

With four weeks until the regular season begins, the Vikings finally have game film to evaluate. And while Friday's 17-6 loss at San Francisco didn't provide a huge body of work to analyze, at least it's something.

The first-string offense, playing without Percy Harvin and Adrian Peterson, played two possessions and scored on both.

The defense, meanwhile, went without veterans Jared Allen, Kevin Williams and Antoine Winfield (all healthy scratches) and was steamrolled on its first two series.

So what else do you need to know as the Vikings return to Mankato to resume training camp practice Sunday? Here's the breakdown:

OffenseReason for optimism: Second-year quarterback Christian Ponder had only one pass -- a 52-yard strike to Stephen Burton -- that was worthy of inclusion on the highlight reel. But overall, Ponder did exactly as the Vikings wanted. When he had time, he went through his reads and found the right receivers. When he was pressured or everything was covered, he either threw the ball away or scrambled for a short gain. On two possessions, Ponder led the Vikings to a pair of field goals. He didn't turn the ball over. And he didn't take a sack. Of his five incompletions, two were balls he threw away to avoid making a costly mistake. The other three hit receivers in the hands. Overall, Ponder's mental growth seemed evident.

"Last year, I had way too many turnovers," he said. "It's something I'm trying to work on -- being smarter with the ball."

Worth discussing: The refurbished first-unit offensive line seemed to hold up well. Ponder had high praise for rookie Matt Kalil and called the line's overall play "outstanding."

"I had so much time back there it was unbelievable," the Vikings quarterback said.

The line also helped Toby Gerhart plow for 31 yards on five rushes. Head coach Leslie Frazier lauded Gerhart's effort, too.

"We've avoided contact with him in training camp -- haven't wanted to take him down," Frazier said. "And to see how forceful he ran the football and his presence [was encouraging]."

DefenseReason for optimism: Not many bright signs surfaced on a night in which the Vikings allowed 412 total yards. But with questions looming about the depth at linebacker, the backups played well. Tyrone McKenzie recorded a game-high six tackles. Marvin Mitchell forced a fumble on tight end Garrett Celek and also stopped 49ers back Rock Cartwright for a 6-yard loss. Rookie Audie Cole delivered a sack and Solomon Elimimian delivered the Vikings' lone takeaway, a fourth-quarter interception in the red zone.

Explained Frazier: "There were a couple of times as a whole where we didn't take good angles to the football. And that ended up hurting us."

Worth discussing: Starting nose tackle Letroy Guion suffered a posterior cruciate ligament injury in his knee on the defense's first series and, according to Frazier, will likely be out a week or two. Thankfully, for the Vikings, Guion's injury doesn't appear to be severe. But given Guion may not play in the next two preseason games, the Vikings' lack of depth at nose tackle will be exposed. Fred Evans will move into a starting role but has been ordinary through his first six seasons in the NFL. Behind Evans, rookie Trevor Guyton will see more action. But Guyton, a seventh-round pick, has faced a steep learning curve so far and certainly isn't ready to take on regular playing time in the NFL.

Special teams Reason for optimism: The wind was swirling Friday at Candlestick Park, one of the least friendly NFL venues for kickers. Yet rookie Blair Walsh came in and nailed first-half field goals of 39 and 26 yards.

"This was not the optimal position to be in as a rookie, coming into these windy conditions," Frazier said. "But he handled it well."

Walsh also kicked off three times, putting one out of the end zone and the other two deep. The 49ers' average starting field position after Walsh's kickoffs was their own 18.

Worth discussing: Chris Kluwe got plenty of work Friday. He averaged 40.3 yards on six punts.

dan.wiederer@startribune.com