The move of Mike Bell atop the Broncos' depth chart is to me obviously meant to "send a message" to Tatum Bell and Ron Dayne. Much in the same way Mike Shanahan so effectively "sent a message" to Ashley Lelie in the early part of the offseason, and how he "sent a message" to Jake Plummer by taking The Gunslinger with the 11th overall pick.
I fail to see the logic behind continuing to make it apparent that you have no respect for the players that play under you and that you will show them absolutely no loyalty whatsoever. It would be one thing if Tatum Bell had been playing poorly and Mike Bell was somebody who had actually played a down in an NFL game, or was actually perceived to be good enough by a single scouting department to be worth a seventh round draft pick.
Shanahan obviously doesn't have confidence in Mike Bell, as evidenced by the fact that Thomas Jones' name keeps popping up in trade discussions with Chicago for Ashley Lelie.