Ellis was a Human baseball player in 1957 on a team with Wilcox. Ellis was a right fielder with the team.
In one game broadcast on the radio, and overheard by Mestral and T'Mir in Carbon Creek, a player from the opposing team, Dix, hit a scorcher down the right field line, past the first baseman. It was fielded by Ellis who threw the ball to Wilcox. Thompson, a teammate of Dix, had rounded third base and collided with Wilcox, but he was called out. (ENT: "Carbon Creek")
This character was only mentioned in dialogue.
Since "Carbon Creek" takes place in October 1957, the only possible baseball game on the radio that month (after the end of the professional season) would have been a World Series game; the 1957 World Series was contested by the New York Yankees and Milwaukee Braves. In real-life, neither team had anybody named Wilcox, Ellis, Dix on their roster (though "Thompson" may be the Braves' Bobby Thomson).