METAIRIE, La. - The New Orleans Saints and free agent running back C.J. Spiller agreed to a four-year contract on Friday, a move that bolstered a backfield which also includes Mark Ingram and Khiry Robinson.

Spiller, 27, has spent his first five NFL seasons with the Buffalo Bills, showing the ability to pile up yards as both a ball carrier and receiver out of the backfield.

His best season came in 2012, when he rushed for 1,244 yards and six touchdowns to go with 459 yards and two TDs receiving. He followed that up with 933 yards rushing and 185 yards receiving in 2013, but played in only nine games last season because of a shoulder injury, finishing with 300 yards rushing and 125 yards receiving.

Financial terms were not released.

The Saints also have traded receiver Kenny Stills to Miami for linebacker Dannell Ellerbe and a third-round draft pick, and released defensive back Corey White, who was a fifth-round draft choice in 2012.

The arrival of Spiller, a former Clemson standout, comes on the heels of New Orleans' decision to release veteran running back Pierre Thomas, who often played on third downs because of both his versatility as a pass-catcher and his blocking ability.

Ingram, who rushed for 964 yards and nine touchdowns last season, often played on first or second downs, while Robinson, who rushed for 362 yards and three touchdowns, was inserted more sporadically on plays that suited his powerful running style.

The Saints, who went 7-9 last season, have made a flurry of moves in the past week or so that has resulted in a significant roster shuffle and the stockpiling of draft picks.

New Orleans has either traded away or released five prominent players: tight end Jimmy Graham, left guard Ben Grubbs, middle linebacker Curtis Lofton, Thomas and Stills. White was also a regular, though usually a reserve unless pressed into starting roles by injuries.

The trades of Graham, Grubbs and Stills have brought in centre Max Unger and Ellerbe, as well as additional draft picks in the first, third and fifth rounds. Following the Stills trade, the Saints had nine total draft picks in the seven rounds of this year's draft, having given up only their fourth rounder as part of the Graham deal.

Meanwhile, New Orleans has been able to bring prominent free agents on both sides of the ball — Spiller on offence and cornerback Brandon Browner on defence.