2.) Speed after catch
Something that the Bills have lacked in previous years has been speed at the receiver position. Aside from Isaiah McKenzie, the Bills wide receiver core has not necessarily had the speed on the perimeter.
When a team has a big-armed quarterback like Josh Allen who can launch it 70-plus yards, coaching staffs want to try and have a weapon that can break away for a big gain. Isabella displayed speed throughout the preseason, specifically against the Indianapolis Colts when a linebacker tried to cover him and Isabella had an extra step on him and broke for a bigger gain.
The Bills already have arguably the best route runner in the league with Diggs, a big weapon on the outside in Davis, and even another speedster with Harty. Why not have another speedster as a relief player on the offense? One factor to keep in mind is that Isabella would not even need to go long to make a big play. He has the 4.3 speed to be a security blanket and turn it up the field for a bigger gain.