https://www.whatifsports.com/gd/TeamProfile/Stats.aspx?tid=51063

Is there a reason my backup rb is performing so well, last game was just ridiculous he scored 6 TD's on 20 carries

I'm a very run heavy team and he performed well last season too but this season he has just gone off, I know I have a terrible schedule, but he's outperforming my starting running back who is putting "solid" stats considering his carries and competition. My starter is 2nd in carries 1st in yards 2nd in avg ypc for 100+ carries and 1st for 200+ carries and T-4th in TD's

My backup is leading the nation in rush touchdowns with 15

If someone can explain why or just confirm its my terrible sos and explain why my starting isn't putting up such monstrous stats that would be appreciated

My guess is during a medium to long drive your starter is substituted out when you are in/near the red zone.

Nothing definite. But good likely hood, by time your backup comes in , the defense is running on fumes. Down to 85 percent or less. So , suddenly your backup becomes a stud.
I have had the backup excel MANY times and often it seems that is the reason;.

Combination of what marlove and mojo (crypt) said.