For those of you who are on the "It wasn't the coaching, you have to earn your spot" bandwagon..
On 1st down in the 4th quarter, if a team is in a one-score game, they run the ball 53% of the time. The Colts ran the ball 64% of the time, 3rd most in the NFL. This despite the fact that on 1st down runs they recorded just a 35% success rate (2.5 YPC), while they were successful on 53% of their passes with 7.8 YPA.
In these 4th quarter runs, an older Frank Gore posted just a 30% success rate. A younger, fresher Marlon Mack recorded a 57% success rate, but received a third of the carries that Gore received. As the data shows, potentially due to overuse and wear & tear, Gore was clearly less fresh than Mack, but was still used 3 times more often.