2. Casey Hayward
Keeping Taysom Hill would've been fun, but the Packers offense was fine without him. The same can't be said about the secondary after parting ways with Casey Hayward.
The Packers believed they had enough cornerback depth to move on. Sam Shields was their top corner, while Damarious Randall and Quinten Rollins had shown potential in their rookie seasons. Hayward, meanwhile, had previously battled injuries and played mostly in the slot for the Packers.
Green Bay let him go. Big mistake.
Hayward went to his first Pro Bowl and was named a second-team All-Pro in his first season with the then-San Diego Chargers, leading the league with seven interceptions. He would back it up with the same honors the following year.
Without him, the Packers pass defense fell apart. They ranked 31st against the pass in 2016, then gave up 180 yards and two touchdowns to Julio Jones in the NFC Championship Game. It forced them to draft Kevin King the following offseason, but Green Bay's defense improved to just 23rd against the pass in 2017.
Not only did Hayward become a better player after leaving Green Bay, but the Packers defense took a huge step back without him, costing them in the playoffs.