Sanchez sustained a shoulder injury in the win, which will keep him out of his side's final warmup game this week and leaves him doubtful for their season opener.
Namath told The Rich Eisen Podcast: "You do not put your quarterback in there in that situation, not the guy that is probably going to be your starter behind a makeshift offensive line in a pre-season game.
"Come on. There was no rhyme or reasoning to that."
New York open their regular season campaign against the Tampa Bay Buccaneers on September 8.