Because Allen is a proven, consistent starter who’s also a leader and a Pro Bowl player. Chase and Montez, while showing flashes, never shown consistency. They are both great players, don’t get me wrong, but as fans we are overvaluing two DEs whose career high in sacks in a season are 7.5 and 9. Numbers wise, both of them might actually have the best seasons of their careers, but they are both playing on a 31st ranked defense while sharing a DL with two pro bowl DTs.
Realistically speaking, how hard is it to switch a longsnapper mid season? How long would it take for Tress, Slye and the new guy to get the timing right? Can’t be much worse than this. Tress has saved us from so many bad snaps already.