SAN DIEGO -- Getting ready to board a flight back to the Twin Cities, but wanted to throw out a few thoughts before the office water-cooler mourning begins:

Top three concerns after Sunday's 24-17 loss to the Chargers:

OFFENSIVE LINE: I thought the offensive line was the Vikings' biggest concern heading into the season. I put it above the quality and depth at corner, and the unsettled safety positions. A solid performace in the third preseason game against Dallas led me to believe that maybe, quite possibly, the line wouldn't be a train wreck.

Well, for one week, particularly one half of one week, the offensive line at least bordered on train-wreck bad. Yes, the Vikings ran the ball well in the first half. Yes, they led by 10 points against a Super Bowl contender.

But the pass protection was horrendous, even when the Vikings went to max protect. That's a serious issue because nobody in the NFL can win strictly by running the football down. Not even teams with $100 million running backs.

The Chargers were steamrolled for 125 yards rushing on 16 carries (7.8) in the first half. But they held the Vikings to 24 yards on 10 carries in the second half.

COVERING BACKS OUT OF THE BACKFIELD: I feel kind of bad picking on the defense in any way. It played well enough long enough to win, But when the offense went AWOL, the defense faded. This was the first game of the season and guys haven't played a full game in nine months. So the defense understandably wore down. The coaches rotated players in generously, but all that did was put second-line players up against a high-powered Chargers' offense that was finding its rhythm.

However, as coach Leslie Frazier said after the game, the Vikings need to find out why the defense reacted so slowly to running backs catching balls out of the backfield. Fullbalk Matt Tolbert, a bowling ball in shoulder pads, caught nine passes for 58 yards and two touchdowns. Running back Ryan Mathews had three catches for 73 yards, a 24.3 average.

Granted, the Vikings were playing a zone designed to take away the deep ball. That's a big part of what they do. But when an opponent is killing your game plan by passing underneath the coverags, ya gotta change things up.

HALFTIME ADJUSTMENTS: The details aren't as significant as the fact the Chargers' coaches obviously had a better halftime than the Vikings' coaches.

Offensively, the Vikings were limited to 26 yards and two first downs in the second half. They had two passing yards and ran only 17 plays. That's remarkably inept.

Defensively, the Vikings started missing tackles and making dumb penalties right out of the gate in the second half. Again, the defenders were getting tired because the offense was invisible. But the Chargers had 234 yards of offense in the second half. Rivers threw for 193 yards in the second half. The Chargers also had 18 first downs in the second half, including three by penalty.

On the drive that clinched the game for the Chargers, the Vikings jumped offsides three times. THREE. Letroy Guion did it twice, including once on second-and-three. Fred Evans then effectively ended the game when he jumped on third-and-two with two minutes left. The Chargers took a knee after that.

Rivers has a tremendous hard count, but come on. Three offsides in a span of seven snaps?

The good news is despite a pitiful second half, the Vikings were competitive on the road against a Super Bowl contender. But the coaches have a lot of work to do to keep this team from quickly losing sight of the rest of the NFC North.