The Lions' biggest offseason need is a running back, according to former NFL general manager Bill Polian, now an analyst for ESPN. "Detroit is a dominant running back away from having a dynamic offense," Polian writes. "Whether the Lions get that player in free agency or the draft remains to be seen, but they need one. Just imagine how much more effective WR Calvin Johnson could be if the defense had to divide its attention more?" Former Heisman Trophy winner Reggie Bush is among the free-agent running backs, and Lions receiver Nate Burleson is publically lobbying for him to sign with Detroit. Bush, 27, rushed for 986 yards on 227 carries (4.3-yard average) for the Dolphins in 2012. He also caught 35 passes for 292 yards. The only running back among the ESPN Scouts Inc.'s rankings of the top 32 draft-eligible players is Alabama's Eddie Lacy at No. 30. From The Detroit News: