The Lions say trade conditions put Roberts back on the team's roster before they took him off it for the second straight day.
Roberts failed a physical with the Patriots, according to a person aware of the situation who spoke to The Associated Press on the condition of anonymity because that detail was not announced. Roberts declined comment when reached by the AP on Friday.
Detroit announced Thursday it received a conditional pick from New England in exchange for Roberts. He became expendable this offseason after the Lions drafted Iowa tight end T.J. Hockenson early in the first round and signed veterans Jesse James and Logan Thomas.
Detroit drafted Roberts in the fourth round in 2017. He has 13 career receptions for 146 yards and three touchdowns.
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