Jackson, who played the entire second half of Thursday's preseason win over the Colts, completed just two of 10 passes for 45 yards.
Jim Kubiak of The Buffalo News noted that the rookie looked "unsteady and visibly behind several read and throws." The 6-foot-7 Jackson has a monster arm and plenty of upside, but he's nowhere near No. 2 quarterback Matt Barkley at this stage, and his best hope for 2019 is if the Bills decide to roster three quarterbacks instead of two.