When we use one of, the object of the prepositions is a group that the one belongs to.
One of the players is my brother.
One of the team is my brother.
One remains the subject; thus, subject-verb agreement requires the subject to have an –s for the third person singular present tense.
One of the players has the ball.
One of the swimmers races for our team.
The group that the one belongs to must be a countable noun or a unit which has countable members such as a dance troupe, a team, an organization, or a class. The countable group such as players or students is plural; however, the unit such as team or troupe is singular.
In the sentence
One of the greatest players is Barry Bonds.
Players is plural even with the use of the superlative, greatest. If we want to say that Barry Bonds is the greatest player, we would not use one.
Barry Bonds is the greatest player. (No other player is as great as Barry Bonds.)
Barry Bonds is one of the greatest players. (Barry Bonds belongs to the group of greatest players.)
When we have a uncountable noun in this construction, we have to use the countable member or quantity to use this construction.
One of the pieces of luggage is lost.
One of the grains of rice is red.
One of my homework assignments is finished.