This season, the NFL requires that either the team's staring center or the two guards wear microphones during games.
Veteran center Jonathan Goodwin has deferred, so guards Adam Snyder and Mike Iupati are outfitted with the devices that bring alive the sounds of the game. (The microphones remotely switch on after the team breaks the huddle and turn off after each play.)
That's why fans watching at home can hear a lot of what 49ers quarterback Alex Smith says at the line of scrimmage. Everyone has become accustomed to hearing Smith yell a couple of familiar commands: "Let it roll" or "Kill."
Over the past several weeks, some onlookers have believed that the 49ers to run the ball when Smith barks out one command and they throw when he says the other. That simply is not the case.
In the first half of the 49ers' game Sunday against the St. Louis Rams, there were 10 times in which Smith was given two plays to relay to his teammates in the huddle. Based on his pre-snap reads, Smith can either keep the first play ("Let it roll") or change to the second play ("Kill").
There might be two run plays called in the huddle or two pass plays. Or the options could be run and pass -- or pass and run. There is no pattern. And for the defense and fans who can hear Smith on TV, the calls mean nothing unless you know which two play calls -- in which order -- were called in the huddle.
Case in point: In the first half, the 49ers ran twice and passed four times on the "Let it roll" command; and they passed twice and ran once on "Kill."
San Francisco 49ers
Find the latest San Francisco 49ers news, highlights, analysis and more with NBC Sports Bay Area and California.
OK, now that we got that out of the way . . . Here is the entire offensive player-by-player review from the 49ers' 26-0 win over the St. Louis Rams on Thursday:
Quarterback
3-Scott Tolzien: Inactive (coaches' decision).
7-Colin Kaepernick: He entered with 7:20 remaining in the game and played the 49ers' final six snaps of the game. He was 0-for-2 in passing attempts with an incompletion off tight end Justin Peelle's hands and a high throw to Delanie Walker. (Follow on Twitter @Kaepernick7)
11-Alex Smith: Made his 12th start of the season and had, statistically, his best game of his 71-start NFL career. Smith compiled a passer rating of 142.3 with a 17-of-23 game for 274 yards with two touchdowns and no interceptions. . . . He was sacked four times (he probably held onto the ball too long on one of them) and a couple of his incompletions were the results of pressure in his face. . . There were also two dropped passes on well-thrown balls. . . Made perfect deep throw to Vernon Davis that was dropped in the end zone. The pass was impressive on a couple of different levels: It was perfectly placed as it traveled 50 yards in the air, and Smith hung in to make the throw just before defensive tackle Fred Robbins hit him. . . . He also gained 8 yards on an option-read run play.Running backs
21-Frank Gore: He started at running back and played 37 snaps before leaving the game for good after his first carry of the fourth quarter. . . Gore became the 49ers' all-time leading rusher since the franchise entered the NFL in 1950, surpassing Joe "The Jet" Perry's total. Gore gained 73 yards on 21 carries. He did not catch a pass. . . Picked up blitz of safety Quintin Mikell to allow Smith to throw 12-yard pass to Ted Ginn to convert a third-and-4 situation.
24-Anthony Dixon: He played four snaps of offense. He was on the field for a failed "Wildcat" play with Kendall Hunter taking the direct snap. . . On the final drive, he carried three times for 2 yards. . . He also played special tams. (Follow on Twitter @Boobie24Dixon)
32-Kendall Hunter: He played 28 snaps in the game, and had five rushing attempts for 4 yards. . . . He took the direct snap in a "Wildcat" play that lost 7 yards in the third quarter. . . He also caught two passes for 24 yards. . . . Did a good job in pass protection. He picked up blitz on safety James Butler to allow Smith to get the ball out to Kyle Williams on his long TD catch.
44-Moran Norris: Inactive (coaches decision).
49-Bruce Miller: Started at fullback and played 30 snaps. . . Cut down linebacker Chris Chamberlain with a block that opened way for Gore to pick up 8 yards on first rushing attempt of the game. . . . Also played special teams. (Follow on Twitter @bmiller_49)
90-Isaac Sopoaga: He saw action on two snaps of offense and had a good block on a run play inside the 5-yard line on which Gore nearly scored.Wide receivers
10-Kyle Williams: As the team's No. 3 receiver, he played a career-high 34 of the team's 63 offensive snaps. He caught two passes for 66 yards, including a 56-yard touchdown. . . . He also fielded one fair catch as a punt returner. . . . Reached out to make catch away from defense for 10-yard gain in first quarter on a third-and-5 play. . . . Penalized for an illegal block in the back on a 19-yard Ginn completion. . . Showed his speed on a reverse that he turned into a 25-yard gain, a play that ended with a devastating stiff arm of Mikell. . . . Caught 8-yard hitch, got to the inside against cornerback Josh Gordy and took it 56 yards for a fourth-quarter touchdown. (Follow on Twitter @KyleWilliams_10)
15-Michael Crabtree: Started at flanker and played 40 snaps. He caught four passes for 96 yards, including a 52-yard TD in the fourth quarter. . . Dropped pass on a third-and-7 play that likely would've picked up a first down in first quarter. . . . Ducked out of tackle attempt of cornerback Justin King to pick up final 10 yards on a 15-yard gain. . . Made block on safety Craig Dahl downfield on play in which Gore gained 20 yards. . . . Made nice stutter move and ran deep post to beat King for his long TD catch in the third quarter. (Follow on Twitter @KingCrab15)
17-Braylon Edwards: Inactive (kneeshoulder). With one week off to rest up, there is a good chance Edwards is available for action Sunday against the Cardinals. (Follow on Twitter @OfficialBraylon)
18-Brett Swain: Suited up for the second time this season and saw action on seven snaps from scrimmage as the 49ers' No. 4 receiver.
19-Ted Ginn: Started and played 34 snaps in the game. He caught four passes for 56 yards, and added another 16 yards on a "fly sweep" run play in the third quarter. . . Picked up Vernon Davis' fumble at end of the first half to enable 49ers to retain possession. . . Averaged 6.3 yards on three punt returns, and had one kickoff return for 31 yards.Tight ends
46-Delanie Walker: Played 37 snaps as the team's No. 2 tight end. . . He had two passes thrown his way but did not have a reception. . . . He also played special teams. . . . Took pitch on a reverse and made Mikell miss 3 yards behind line of scrimmage on play that gained 14 yards. . . Good protection one-on-one against defensive end James Hall on Smith's long TD pass to Crabtree. (Follow on Twitter @Dwalk46)
81-Justin Peelle: Entered as the No. 3 tight end and played seven snaps from scrimmage. . . He was targeted on a pass from Kaepernick that deflected off his hands in the fourth quarter.
85-Vernon Davis: Started at tight end and played the first 57 snaps of the game before heading to the sideline for the final two 49ers possessions. . . . He caught five passes for 32 yards, but let a big one get away. . . Picked up 9 additional yards after making Chamberlain miss tackle in first quarter on a 13-yard gain. . . . Got behind safeties Mikell and Craig Dahl but dropped perfectly thrown pass in the end zone for what would've been a 40-yard TD in the second quarter. . . . At end of 15-yard completion late in the first half, had the ball stripped but Ginn recovered. . . . Very good block on Long to allow Williams to get around right side for 25-yard gain on a reverse. . . (Follow on Twitter @VernonDavis85)Offensive linemen
59-Jonathan Goodwin: Started at center and played all but the final three-play possession of the game for the 49ers. . . Got block on Robbins to get Gore to next level on a play that went for 20 yards in the second quarter. (Follow on Twitter @Jgoody59)
62-Chilo Rachal: Played seven snaps at guard in the second half, including three snaps at left guard for the first time in his career. One the next possession, he switched to right guard.
67-Daniel Kilgore: Inactive (coaches' decison).
68-Adam Snyder: Started at right guard, where he remained for the entire game until he switched to center for the first time in his NFL career. He played the final three snaps at center. . . . Called for false start before a fourth-and-2 play in the second quarter to move the 49ers back and force a punt. . . . Blocked Robbins, then got to second level to take care of middle linebacker James Laurinaitis on a play in which Gore gained 20 yards in the second quarter. . . . On next play, Robbins got pressure inside that contributed to Chris Long's sack vs. Anthony Davis. . . Surrendered pressure to James Hall to force an incompletion. . . . Blocks on defensive tackle James Hall and safety Craig Dahl to allow Gore to pick up 6 yards on sweep in third quarter. (Follow on Twitter @ASnyds68)
74-Joe Staley: Started at left tackle and played all but the final two possessions. . . . He had a good showing all day against Rams defensive end James Hall. . . He capped the day with a glancing Gatorade dump on winning coach Jim Harbaugh. (Follow on Twitter @jstaley74)
75-Alex Boone: He played three snaps as an extra blocker, and finished off with the final two possessions at left tackle.
76-Anthony Davis: Started at right tackle and played every snap. . . Good block on Long to enable Gore to pick up 8 yards on first play of the game. . . . Good block on Long on Gore's 20-yard gain. . . .On next play, Long used a spin move to get past him and throw Smith for a sack of 2 yards. . . . That drive ended when Long got pressure on Smith to force incompletion on third down. . . . Long beat him with an inside move on final play of second quarter for his second sack. (Follow on Twitter @AnthonyDavis76)
77-Mike Iupati: Started at left guard and played all but one possession on offense. . . . He tied up Long when he pulled to right side, allowing Gore to pick up 5 yards. . . . Called for two holding penalties within three plays late in the first half. . . Hall beat him for a third-quarter sack.
78-Mike Person: Inactive (coaches' decision).