Dennison's play-calling was questioned after Buffalo scored just three points against Jacksonville in the franchise's first playoff game in 18 years.
Dennison was hired onto head coach Sean McDermott's staff last January after Rex Ryan left Buffalo. They ranked 29th in the league in total yards (302.6 yards per game) and 22nd in scoring (18.9 points per game), while averaging an abysmal 176.6 passing yards per game.
The team announced the move on Friday. But McCoy took the Green Bay Packers' offensive coordinator job and was sacked midseason. There are some early candidates, including former Seattle Seahawks offensive coordinator Darrell Bevell and Alabama offensive coordinator Brian Daboll, who has western NY ties.
McDermott was non-committal when discussing potential coaching staff changes during the season-ending news conference on Tuesday.
"It'll be a collaborative deal, [but] at the end of the day, it'll be my decision to make", Beane said. "We're still in the process of getting that accomplished".
"We're building this thing together", McDermott said then.
While the Bills gained just 263 total yards in the playoff game against the Jags, they were particularly chastised for the run-pass option called on first-and-goal from the Jacksonville 1-yard line in the second quarter.
The Buffalo Bills ended their 17-year playoff drought this season but bowed out in the wild-card round. But there is one interesting connection: McDermott and McCoy have the same agent, Bob LaMonte. However, it also has been widely speculated that the Bills also will strongly consider making a change at quarterback and moving on from Tyrod Taylor this offseason.