Tampa Bay Buccaneers quarterback Josh McCown throws a pass against the St. Louis Rams during the first quarter of an NFL football game Sunday, Sept. 14, 2014, in Tampa, Fla. (AP Photo/Chris O'Meara)

Tampa Bay Buccaneers quarterback Josh McCown (12) celebrates with wide receiver Vincent Jackson after scoring on a 1-yard touchdown run against the St. Louis Rams during the third quarter of an NFL football game Sunday, Sept. 14, 2014, in Tampa, Fla. (AP Photo/Brian Blanco)

Tampa Bay Buccaneers quarterback Josh McCown (12) eludes St. Louis Rams defensive end Robert Quinn (94) during the second quarter of an NFL football game Sunday, Sept. 14, 2014, in Tampa, Fla. (AP Photo/Phelan M. Ebenhack)

Tampa Bay Buccaneers quarterback Josh McCown (12) is upended by St. Louis Rams cornerback Janoris Jenkins (21) as he dives over the goal line to score on a 1-yard touchdown run during the third quarter of an NFL football game Sunday, Sept. 14, 2014, in Tampa, Fla. Defending for the Rays is free safety Rodney McLeod (23). (AP Photo/Phelan M. Ebenhack)

Tampa Bay Buccaneers running back Bobby Rainey (43) runs between St. Louis Rams defenders T.J. McDonald (25) and Jo-Lonn Dunbar (58) during the second quarter of an NFL football game Sunday, Sept. 14, 2014, in Tampa, Fla. (AP Photo/Phelan M. Ebenhack)

St. Louis Rams quarterback Austin Davis (9) is sacked by Tampa Bay Buccaneers defensive tackle Clinton McDonald (98) during the third quarter of an NFL football game Sunday, Sept. 14, 2014, in Tampa, Fla. (AP Photo/Phelan M. Ebenhack)

Rainey, who was a useful fantasy runner for part of last season, is again playing a bigger role with Doug Martin (knee) out of action. He thrived against the Rams, rushing for 144 yards. With a short week ahead (the Buccaneers face the Atlanta Falcons on Thursday Night Football), Martin is no lock to be back in the lineup for Week 3. Such a scenario would make Rainey a legitimate flex starter for owners.