You can see the efficiency of all running backs tends to regress to the mean, not just those coming off seasons with heavy workloads. If a back runs for 6.0 YPC in a year, he will probably see a decline in efficiency whether he had 50 carries or 400.

Thus, while the production of a running back coming off a season with a heavy workload is likely to decrease, it is not a legitimate reason to avoid that player in fantasy drafts. The (probable) decrease in production is due to the previous season being a statistical outlier (a result that is unusually far from the mean).

The best way to look at the situation is this: what is the running back’s chance of generating production that is comparable to the previous year? It is actually the same as it was prior to the start of the previous season, i.e. the workload has no noticeable effect on his ability to produce.

For example, if a running back has a 20 percent chance of garnering 2,000 total yards in a season, that percentage remains stable (assuming his skills level does the same) from year to year. Thus, the chance of this player following a 2,000 yard season with another is unlikely, but not due to a heavy workload (a necessity for such productive output), but rather the fact that he only had a 20 percent chance to do so from the start. We wrongly (and ironically) attribute the decrease in production to the player’s prior success when, in reality, no such causal relationship exists.