Even if Indianapolis hadn't traded for Trent Richardson on Wednesday, the 49ers still would have a tough time beating the Colts on Sunday.
Look at the facts: The Colts ranked fifth in the NFL in rushing yards without Richardson. They average 5 yards per carry. To beat the 49ers, you have to run the ball well and that's what the Colts do. They probably could have run on the 49ers with the running backs they had already, Ahmad Bradshaw and Donald Brown, but Richardson is better than both of them.
Forty Niners defensive coordinator Vic Fangio gushed about Richardson: "He's strong. He's fast. He's got a good stiff arm. He's a move-the-pile kind of guy, but he's also got some shiftiness too where he can bounce it outside or inside."
Gee, the 49ers could use a running back like that.
Expect Richardson to run on most first and second downs like Marshawn Lynch did Sunday night. And on third downs, expect Andrew Luck to play much better than Russell Wilson did last week.
The 49ers' defense forced Wilson to stay in the pocket and he struggled because he's short. Luck isn't short and doesn't struggle in the pocket. He succeeds in the pocket. Expect Luck and the Colts to convert more than half of their third downs and score at least three touchdowns.
Can the 49ers' offense keep pace?
I don't see how it can.
It's a run-first offense without a running back. Frank Gore's legs aren't coming back. You've seen Gore play this season. Can you picture him breaking out around either end of the formation on a pitch or sweep? Maybe a year ago but not now.
When Gore takes a handoff, the defense doesn't have to worry about him bouncing a run outside because his legs have no bounce and he's slow. If he's going to be effective he has to run up the middle.
That's why the 49ers have to use the Pistol formation. They need the implied threat of Colin Kaepernick sprinting around the outside on the read-option. If Kaepernick lined up under center like a traditional quarterback, how would the 49ers run the ball? They wouldn't. They'd be easy to stop – just plug the middle.
And the Colts' defense can plug the middle. They have allowed only 2.5 yards per carry between the tackles this season according to Pro Football Focus. They have three stout defensive linemen – Cory Redding and two former 49ers, Ricky Jean Francois and Aubrayo Franklin.
It is outside the tackles where the Colts' defense is vulnerable, giving up 8.1 yards per carry this season. But Gore can't take advantage of that. Kaepernick is the only 49er currently fast enough to run around the outside against the Colts. You should expect him to carry the ball 10 to 15 times on Sunday.
But the Colts are expecting that, too. They're going to stack the box with eight defenders and try to force Kaepernick to throw the ball like the Seahawks did.
Then, expect the Colts to combo-cover Anquan Boldin with a cornerback and a safety. The Colts don't have someone like Richard Sherman who can single-handedly erase, but double coverage erases most receivers. Expect Boldin to be erased.
The Colts are going to try to force Kaepernick to pass the ball to anyone but Boldin. Vernon Davis pulled his hamstring against the Seahawks. Hamstrings usually take three weeks to fully recover. Sure, Davis still can block but can he get open? Can he outrun linebackers and safeties down the field? Will he further injure his hamstring trying?