Joshua Kelley was the only other running back to receive a carry in Austin Ekeler's absence but it was short-lived as Ekeler not only returned but scored a touchdown and ended up with a decent 70 yards from scrimmage. Unless he misses the week of practices, Ekeler has to be started everywhere in Week 16.
No surprises here really. The Chargers just signed Michel to at least help compliment Ekeler. While the Dolphins cut Michel, it seems like the Bolts aren't totally sold on going with Kelley as the backup, even though he had a nice camp, according to reports. Spiller was banged up a bit this offseason so he'll likely need more time before he's fantasy relevant and gets to move up the depth chart.
As part of the transaction, the team is releasing Roundtree. Michel should slide right into the RB2 role ahead of Kelly and Spiller. Spiller is battling an injury and while Kelley had a good camp and was winning the RB2 battle, Michel can be considered an upgrade and should form a nice compliment to Ekeler.
With Ekeler the lead back, right now Kelley is the team's RB2. However Spiller could be ready to go for Week 1, and if not, it should only be a matter of time before Spiller moves up the depth chart. It was also reported Sony Michel, recently released by the Dolphins, was in town to meet with the Bolts, so this is something to monitor.