CSN Bay Area

Greg Roman, the 49ers’ offensive coordinator for the past four seasons under coach Jim Harbaugh, has agreed to join Rex Ryan’s staff in the same position with the Buffalo Bills, a source told CSNBayArea.com.

Roman is scheduled to fly on Monday from Florida to Buffalo, New York, where he will sign the contract, the source said. The Bills on Monday announced Ryan as the team’s head coach, replacing Doug Marraone, who opted out of his contract after the season.

Ryan and Roman had extensive talks since the end of the season about joining forces if Ryan landed another head-coaching job after being fired by the New York Jets, the source said.

With Roman as offensive coordinator, the 49ers advanced to the NFC Championship game in the first three seasons with Harbaugh as head coach. The 49ers’ offense struggled this season, and quarterback Colin Kaepernick’s production decreased.

Before the final game of the season, 49ers right tackle Anthony Davis expressed criticism of Roman. Weeks earlier after the 49ers’ 19-3 loss to the Seattle Seahawks on Thanksgiving night, the college-aged daughter of 49ers general manager Trent Baalke tweeted: “Greg Roman can take a hike. . . the 49ers don’t want you no more.”

Ryan and Roman spent two seasons (2006-07) on Brian Billick's Baltimore Ravens staff when Ryan was defensive coordinator and Roman was the assistant offensive line coach. The 49ers, with Roman as offensive coordinator, faced Ryan's Jets in Week 4 of 2012. The 49ers rushed for 247 yards in a 34-0 victory.

The next week, the 49ers became the first team to pile up more than 300 rushing yards and 300 passing yards in the same game – a 45-3 victory over the Buffalo Bills.

The 49ers last season ranked 20th in the NFL in total yards, including No. 4 in rushing. The Bills ranked 26th, and were 25th in rushing. Quarterback Kyle Orton told the Bills he plans to retire, possibly leaving the position up to E.J. Manuel, a first-round pick in 2013 who Marrone benched four games into last season.