The Lions would be wise to protect Jahvid Best’s head. (Leon Halip/Getty Images)

And the question of when Best can return to the field for Detroit may soon become an if.

Mike Freeman of CBSSports.com reported on Wednesday that “people close to (Best) are expressing concern to him that he needs to strongly consider sitting out the year.”

Detroit’s (attempted) shuffling at running back this week is a clear indicator that the team is concerned about the short-term effect of another Best head injury. And if you think the Lions — who actually find themselves in the thick of the playoff hunt for a change — shouldn’t be overly cautious with their second-year running back, just watch this video from Best’s junior year at Cal.

On Tuesday the Lions dealt backup running back Jerome Harrison to Philadelphia for Ronnie Brown — or at least they thought they did. When Harrison failed his physical with the Eagles (and Brown failed to show up at Lions practice), he was shipped right back to the Motor City.

(Breaking news: ESPN’s Adam Schefter reported doctors discovered Harrison has a brain tumor during his physical. “Trade might have saved his life.”)

The Lions, who will likely give veteran Maurice Morris the first shot at the majority of Best’s touches, also added James Davis to their practice squad on Wednesday.