Cohn: Promising 49ers opening drive ends with the same old story

SAN FRANCISCO — The 49ers' real offense, its regular-season offense with a few exceptions, played one whole series, and only one, against the Denver Broncos on Thursday night in the first game of the preseason.

Personal note of sympathy: I hope you weren't sucker enough to buy a ticket for that folderol.

Well, anyway, the official offense, the non-Colt-McCoy, Scott-Tolzien-you name-him offense, did play that one series. In the interest of all of us learning something — you and me — here is a detailed play-by-play analysis of the 13 plays that consumed seven minutes plus seven seconds and showed us a thing or two about the offense of the NFC champs.

First-and-10 at the 49ers' 24-yard line: LaMichael James ran around left tackle for 5 yards.

The meaning of the play: No way would coach Jim Harbaugh risk the health and welfare of his starting running back Frank Gore in a silly game like this. So, James was the designated battering ram. Plus, the 49ers need to know if James is a real NFL back or an overdeveloped flea. He's only 5-9.

The 49ers will rest Gore whenever possible this season to preserve him for the playoffs. Second-banana back Kendall Hunter is still unable to play and may not be ready for the season opener against the Packers. And James may have to play a significant role in regular-season games. A gain of 5 yards on the first offensive play was encouraging for the diminutive back and the team.

Second-and-5 from the 29: Much-lauded quarterback, the eloquent and highly-talkative Colin Kaepernick, sprinted to his right and hit tight end Vernon Davis with a laser for 12 yards.

The meaning of the play: This play proved beyond the shadow of a doubt that Kaepernick knows who Davis is. Rumors had swirled through the locker room that Kap — as the players affectionately call him — never had met Davis, even near the Coke machine. Others said Kaepernick simply has a blind spot for the painter/pass catcher.

Kaepernick certainly couldn't see Davis during games last season and used him mainly as a decoy. Maybe the team fitted out Kaepernick with special contact lenses. This play gives the 49ers hope that, when things matter, Kaepernick will throw the ball to Davis.

First-and-10 at the 41: James ran up the middle for 5 yards.

The meaning of the play: This shows James can run up the gut of the defense, right into those big bad men, without getting murdered. The 49ers need a backup back who can run up the middle and keep defenses honest.

Second-and-5 from the 46: Kaepernick hit Anquan Boldin for 10 yards.

The meaning of this play: This reminds us that Boldin is a great possession receiver. With Michael Crabtree out with an Achilles (or without an Achilles), the 49ers need Boldin. He's just what the doctor ordered.

First-and-10 from Denver's 44: James ran up the middle for 6 yards.

The meaning of the play: See first-and-10 at the 41.

Second-and-4 from the 38: Kaepernick hit Boldin for 4 yards.

The meaning of the play: See second-and-5 from the 46.

First-and-10 from the 34: James ran around right end for 9 yards.

The meaning of the play: James is very fast. He's so fast you can't actually see his legs move. They're a blur. Further meaning of the play: Up to this point, the Niners were wasting the Broncos defense. So far, San Francisco's offense had been a precision machine.