Here's how i see it
When Damien and McCoy were both healthy, they wanted to get Williams about 15 touches per game and McCoy about the same.
When Williams got hurt and McCoy got dinged, they certainly didn't plan on increasing McCoy's workload unless they absolutely needed to. Last week they didn't absolutely need to. So they kept him around the same volume and backfilled the other carries to the next man up.
Darwin is still too unproven to trust as a blocker, so putting him in early in games encourages a team like the ravens to attack, and he's just not good enough to be worth it. But they wanted to get him a few game reps so they put him in late.
Darrell Williams hasn't necessarily passed Darwin on the depth chart - or vice versa. They're both ok options like Ware and Charcandrick a few years ago. Darrell is more experienced and has some size so he was the first choice off the bench.
Neither one has earned a "starting" role, despite the fantasy community's wishes. Williams was getting hit in the backfield a ton - yes he averaged a puny yards per carry, but
https://twitter.com/ScottBarrettDFB/status/1176355877428879361?s=09
In my opinion, the running game is not their priority. It's there to create balance for the passing game. Darrell filled in fine but he's nothing special. None of them are, really. Darrell and Darwin both have a chance to prove themselves, but it's still Damien and McCoy at the top of the list, and damien's receiving and blocking this year are still better than what the other guys have shown even if his running wasn't.
Note that i own one share of each across different leagues and don't look at any of them as my every week starters, but I'd start McCoy if i needed a good rb2 in that league.
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