If Brown clears waivers, the team will place him on injured reserve with a calf injury.
Flacco was an undrafted rookie from New Haven, a Division II school.
Reese was a seventh-round draft pick from Baylor.
Keiser pleaded guilty to misdemeanor battery in March stemming from an attack on a downtown restaurant employee in December. He was sentenced to probation, ordered to pay a fine and complete 20 hours of counseling for anger management.
Others cut were linebacker Victor Aiyewa, defensive tackle Chas Alecxih, wide receiver Torrence Allen, cornerback Crezdon Butler, safety Alden Darby, cornerback Greg Ducre, wide receiver Javontee Herndon, defensive end Joe Kruger, linebacker Cordarro Law, safety Adrian Phillips, tackle Jeremiah Sirles, linebacker Colton Underwood, guard Craig Watts, guard-tackle Kenny Wiggins, center-guard Khalil Wilkes and defensive end Doug Worthington.
Rookie running backs Marion Grice - a sixth-round draft pick - and Branden Oliver, a free agent, both made the team. That gives the Chargers five running backs.
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