This is an easy one. Penalties assessed inside the 20 in the direction of the goal line are not assessed at face value, but are instead assessed at "half the distance to the goal."
So when the Colts, on offense at the 1 got a false start, they were penalized 5 yards to the 6. When the Steelers reciprocated, because they were inside the 20, they went half way to the goal, from the 6 to the 3.
(As usual, there may be other subtleties and exceptions to the rule, but that is the basic rule.)
SD
Really? That is something that I guess I just missed even after years of football. I always thought the half the distance rule was for situations where the full value of the penalty would take the ball into the endzone.
For example, I thought 5 yard penalty on the 15 would take the ball to the 10 while a 5 yard penalty on the 4 would take the ball to the 2.
You learn something everyday.
This may qualify...
When do penalties switch from five-, 10- and 15-yard varieties to half the distance from the goal line? If the offense was already on their goal line, would penalties have no real effect on their distance to first down? --Hank Jones, Joliet
If a distance penalty, enforced from a specific spot between the goal lines would place the ball more than half the distance to the offender's goal line, the penalty is half the distance from that spot to the goal line. This general rule supercedes any other general or specific rule with regard to enforcement of penalties. An exception would be intentional grounding, which is penalized at the spot of the foul if that spot is more than 10 yards behind the line of scrimmage.
There's always been an element of unfairness to this rule. If the ball is on the two yard line, then any penalty against the defense is basically a one-yard penalty (and automatic first down, in many cases), while a penalty against the offense is fully enforced and marked off accordingly. This means that on a first-down play, a 5-yard offensive procedural penalty becomes a "worse" violation than a flagrant personal foul against the defense.
Not necessarily inside the 20, but less than twice the distance of the penalty from the goal line, so inside the 10 on 5 yard penalties (like offsides), inside the 20 on 10 yarders, and inside the 30 on 15 yarders (like the personal foul Troy took in Cinci, the penalty was assessed at like the 25, so they went half the distance).