In the major leagues, yes, its so you can tell them apart.
They can wear from 0-99, Major League Baseball won't issue uniforms that have triple digit numbers.
Originally they were given numbers to correspond with the batting order.
The players' numbers mean nothing except to the players. The players get to choose which number they want to wear.
http://www.phitenusa.com
Hat
its no longer cool
They wear majestic uniforms on the field
Baseball players wear numbers on their jerseys so they can be identified.At all levels of baseball, players have numbers on their jerseys so fans, sports reporter and baseball officials can see who they are by the number they wear. Many MLB teams also have their last names on their jerseys as well, but not, for example the NY Yankees.
Billy Martin
melvin mora
Drew stubs
Batters wear helmets, catchers wear face masks.