Well, a fourth round pick is generally expected to contribute in the NFL, and teams don't usually take fliers that "early" in the draft because there is a lot of quality in that range. The middle rounds are where NFL teams are truly built, and where solid starters are found annually by every team.
I know they hVe a new coach in Buffalo, but you don't dump a high upside 4th round pick without first finding out whether he can play - even bad guys and cancerous personalities seem to get a shot on the field - if they have enough talent. One game is not a legitimate litmus test for a QB, Regardless of statistics. Neither is a season spent practicing with 2nd/3rd string reps. Cardale will get his shot.