It wasn't that nobody thought the Colts could pull out a close win over a more-talented opponent, the Green Bay game in 2012 proved that they could.
But to win 27-7, in such a physically dominating fashion? Nobody expected that.
The Colts beat the 49ers at their own game, defensively smothering the 49ers' passing attack and pounding the ball on the ground for 179 yards. The defense was the most pleasant surprise, as they kept what was once known as a high-flying offense grounded after a touchdown drive in the first quarter.
Individually, who stood out for Indianapolis in their signature win? That's what we look at in this week's report card.
Andrew Luck: B
Against San Francisco, Andrew Luck didn't have to be a savior, a rare but refreshing sight.
The Colts asked Luck to make the easy throws in this one, to take care of the ball and to convert a few key third downs, all of which he did.
Luck finished 18-of-27 for 164 yards, pedestrian stats at first glance. But Luck took just one sack for seven yards and took care of the ball, a notable emphasis in Pep Hamilton's offense. Luck also added four rushing attempts for 24 yards and now leads the league in run EPA (Expected Points Added).
On the team's 80-yard, seven-minute touchdown drive that put them ahead 20-7, Luck converted three third downs, including the biggest score of the game.
Luck's progression downfield has seemed a touch off over the last few games, but he found the open receivers when necessary in the fourth quarter to clinch the win on Sunday.
Ahmad Bradshaw: A+
Ahmad Bradshaw ran like a man possessed on Sunday, gaining 95 yards on 19 carries for Indianapolis. The seven-year veteran showed excellent vision and patience out of the backfield, which worked extremely well with the Colts' game plan (which consisted of a fair dose of draws). Bradshaw ran well both outside and inside the tackles, making defenders miss and running through contact. He deserves a game ball after carrying the offense in the second half.
Trent Richardson: D+
Take the grade with a grain of salt: Trent Richardson probably shouldn't have been playing in this game at all after joining the team on Thursday. He didn't know the playbook, and it was painfully obvious, as the 49ers played the run heavily when he was in. Richardson wasn't elusive and was impatient, running into the back of the line far too often.
Richardson finished with 35 yards on 13 carries (2.7 YPC) and added a touchdown on the day. He was the only Colt to run for less than 5.0 yards per carry. It's no cause for concern, as Richardson should improve as he gets time with the team.
Donald Brown: B-
Donald Brown ran just three times, but gained 25 yards. He did fail to gain a third-down conversion when Indianapolis called a draw on 3rd-and-1 (my least favorite call of the game).
Reggie Wayne: B+
Reggie Wayne didn't go off in this one and was given a few easy passes in the beginning of the game that boosted his totals. Still, he led the Colts with 63 yards on five receptions, including a couple of key third-down conversions.
Darrius Heyward-Bey: B
The former Oakland Raider returned to the Bay Area Sunday and started out the game like he was on the Northern California revenge tour, catching two key passes for 33 yards on the Colts' initial touchdown drive. Darrius Heyward-Bey would catch two more passes for 19 yards on the team's next field-goal drive, but was limited to just one catch for seven yards in the second half.
T.Y. Hilton: C-
T.Y. Hilton finished with just 13 yards on two catches, his second-lowest total yards of his career (didn't have a catch in Jacksonville last season). Hilton did add two punt returns for eight yards, but overall was taken out of the game by the San Francisco defense.
Coby Fleener: C-
Like Hilton, the 49ers' took Coby Fleener out of the game. The second-year tight end had two catches for 13 yards, both of which came in the first half. One was a tough catch in traffic that netted a first down and the other set the Colts up for their first touchdown. Fleener's blocking left something to be desired, but it's not a role he should really be playing.
Dominique Jones: C+
Dominique Jones was a strong blocker, looking even better than FB Stanley Havili in that regard (who had a decent game himself), but didn't make any impact in the passing game in this one. Of course, the Colts are namely using him as a blocker, and in that role he played well on Sunday.
Run Blocking: A-
The only reason I take a tick off of the Colts' grade for run blocking is due to the inability to open anything up when the Colts tried to line up in power formations.
Overall, the line blocked well, opening up running lanes and giving Ahmad Bradshaw and Donald Brown room to get to the second level. Anthony Castonzo was especially impressive on the left side, especially when asked to get out and move on sweeps and tosses.
Pass Protection: B
For this offensive line, this game was a masterpiece, holding the 49ers to just one sack. Of course, this offensive line hasn't had a very high standard so far this year. They did allow seven quarterback hits on the evening, and Luck was forced to work a little bit of magic from time to time. But overall, it was a positive day for the Colts' offensive line, and Luck had room to find an open receiver more often than you would have expected.
Run Defense: B-
When the 49ers decided to run, they did with ease, running for 115 yards on 23 total carries (5.0 yards per carry). Frank Gore was especially impressive, finishing with 82 yards on 11 carries. However, the 49ers stopped running the ball in the second half after a few unsuccessful tries, as Gore got just three carries for 12 yards in the second half, and the rest of the team managed just one yard on four carries.
Pass Rush: A-
The Colts didn't manage a lot of quick pressure or anything like that, but the team was incredibly disciplined against Colin Kaepernick.
They allowed the stifling coverage of the back four to make Kaepernick move, and then either forced a poor throw or contained him before he was able to use his dangerous speed. The line got sucked into the wrong lane a few times in the first half, but overall contained Kaepernick better than expected after the Terrelle Pryor debacle in Week 1.
Jerrell Freeman: A+
After a couple rough weeks to start the season, Jerrell Freeman was as good as we've seen him on Sunday, racking up eight tackles and a sack. Freeman was used occasionally as a spy on Colin Kaepernick and did a very good job of keeping him contained behind the line of scrimmage and not having room to take off and run. Freeman also fared well in coverage and kept Kaepernick from finding any safety valves when his protection broke down.
Kelvin Sheppard: C+
Kelvin Sheppard played well in the unit at times, but still displays shaky tackling skills and struggles to fight through traffic to get to the ball-carrier. He did finish with a tackle for a loss and a pass breakup, but the Colts will welcome Pat Angerer back with open arms when he gets healthy.
Robert Mathis: A
Robert Mathis recorded a sack-and-a-half on Sunday, raising his season totals to 4.5 and his career total to 96. The veteran pass-rusher continues to be the Colts' most dependable edge-rusher, and was the main catalyst for the Colts' pass rush on Sunday, repeatedly getting close enough to Kaepernick to make him uncomfortable, even if he didn't get a sack on every play.
Erik Walden: C-
Erik Walden was getting beat like a rug in the first quarter, when the 49ers ran the ball down the Colts' throats on their first touchdown drive. The ex-Packer looked just as inept as ever at setting the edge, allowing Frank Gore to get loose for 70 yards in the first half. But Walden settled down in the second half, and his renewed discipline was a big factor in the Colts' ability to contain Kaepernick.
Bjoern Werner: B-
The rookie OLB took some nice steps on Sunday, getting pressure on Kaepernick and staying in his lane more often than not. He had a few missteps, but overall it is definitely heading in the right direction for the former Seminole. Bjoern Werner had just one tackle, but pressured the quarterback several times and looked much more comfortable than he has in previous weeks.
Vontae Davis: A
Based on my initial rewatch, Vontae Davis didn't allow a single completion all day and generally blanketed the entire left side of the field. There was one completion that was nearly allowed in the first quarter, but outside of that play, Davis locked down both Kyle Williams and Anquan Boldin on the outside.
Greg Toler: B+
Greg Toler allowed a couple passes and got pushed around a bit in run defense, but overall, like Davis, smothered his receivers and kept Colin Kaepernick and the 49ers offense from gaining any momentum. The secondary's complete dominance was what won this game for Indianapolis, and Toler was a big part of that.
Darius Butler: A
We don't always cover the slot cornerback in this piece, but Darius Butler deserves a shout out after his big day. He wasn't quite as good as Davis, but didn't back down from Boldin physically and tackled well, as well as picking up a pass breakup.
Antoine Bethea: B+
Antoine Bethea gets a slight tick for gambling on a Kaepernick throw early on that resulted in a 24-yard gain for Anquan Boldin, something that's happened in a couple straight games now. But overall, Bethea was a great clean-up guy for Indianapolis on Sunday, including this huge third-down stop that brought every Colts fan to their feet.
Delano Howell: A+
This year's Melvin Bullitt, Delano Howell filled in for an injured LaRon Landry and impressed everybody.
Howell came on the radar in the preseason when he was extremely active, and his play was even more noticeable on Sunday. Howell wasn't afraid to lay wood on receivers over the middle, but didn't give up any big plays either.
It was fantastic showing by the former Stanford Cardinal, and the Colts may not have had near the success they did without his play.
Pat McAfee: A
An underrated part of the Colts' ability to keep the San Francisco offense at bay, Pat McAfee was back to his 2012 form after an inconsistent couple of weeks to start the season.
McAfee punted four times for an average of 48 yards per punt, including pinning the 49ers inside their own 10-yard line three times. Between that and kickoffs, the 49ers only started one of their 11 drives outside their own 20.
Adam Vinatieri: B
The Colts' grizzled veteran was 2-of-3 on Sunday, nailing 41 and 43-yard field goal attempts but just missing a 51-yarder in the second half.