"It might be me," Sparano said with a chuckle Monday. "I'm not for everybody."
All of the players who have left were long shots to make the team. Quillen signed Thursday and lasted only one practice. A fourth player, tight end Jared Bronson, a rookie free agent out of Central Washington, failed to show up to training camp.
"It has an awful lot to do with passion," Sparano said. "This is a credit to the other guys that are in that locker room: What they are doing right now is really hard.
"If your heart isn't in what you're doing, it does not take long with the heat, with the contact, with the intensity of what we're doing out here, and the way we're doing it, to figure out that maybe this isn't for you."
Once a player reaches that conclusion, it's better for the team that he call it quits rather than keep practicing, Sparano said.
Offensive tackle SirVincent Rogers and safety Ethan Kilmer left camp earlier.
Robinson, a native of Fort Lauderdale, Fla., played in 13 games last year for Toronto of the Canadian Football League, making 25 receptions for 381 yards and one touchdown.
Copyright 2009 by The Associated Press