The Boston Red Sox 10th Player Award was first established in 1975 by the WSBK,TV-38 television station. Channel 38 was a longtime broadcaster of Red Sox baseball.
The criteria for the award is that it should go to the player who has "gone above and beyond" and "most exceeded expectations." The very fact that it is called the "10th Player Award" would seem to indicate that it should probably go to somebody outside of the official starting nine, somebody who has produced nicely in the pinch, filling in for an injured starter or shuffling between positions as needed.
Other good candidates are middle relievers and set-up men, or else pitchers who have moved back and forth between the rotation and bullpen, helping the team win games in both roles; I think Tim Wakefield should receive a special "Lifetime 10th Player Award" when he retires.
Dave Stapleton won the award in 1980, when he stepped in for the injured Jerry Remy at second, batted over .300 and finished runner-up for the rookie of the year. Marty Barret won it in 1985, after also breaking into the line up at second base. Joe Hesketh won the award in 1991, when he shuffled between the rotation and bullpen, leading the league with a .750 winning percentage as he went 12-4 with a 3.29 ERA.
Steve Lyons won the award in 1985 and Bob Zupcic in 1991, while putting up fairly mediocre offensive numbers but also playing exceptional defense in the outfield as emergency starters.
But it is a fan voted award, and sometimes the selections have simply been popular stars. Roger Clemens won the award in 1986, the very same year he won the league MVP and his first Cy Young. Clemens had exploded onto the scene that year, so it could be argued that he "exceeded expectations" despite being a prized prospect.
Dwight Evans won the award in 1987, for the second time, after a year when he was among the most productive offensive players in the league and well after he had established himself as a star. In Dewey's case, it was almost as if he won the award due to the fact that Sox fans felt like the rest of the world didn't appreciate him enough. He took home the award again in 1988 and remains the only three-time winner.