Brunell was due to make $1.25 million this season, and there's a strong possibility of re-signing him at a lower salary. The Jets, preparing for the possible arrival of free-agent cornerback Nnamdi Asomugha, made the move to clear cap space.
Brunell wasn't the only quarterback on the way out of Jets camp. New York also released backup Kevin O'Connell, who is coming off shoulder surgery.
If they don't re-sign Brunell, the Jets would have to shop for an experienced backup. Because of the lockout, it would be difficult to break in a new quarterback and there aren't many options left on the roster.
McElroy agreed to terms on a four-year deal Friday, according to a league source.
Brunell, who turns 41 in September, appeared in only two games last season, but he was a mentor to Sanchez, who has talked glowingly of Brunell's impact and steadying influence.
Rich Cimini covers the Jets for ESPNNewYork.com.