Veteran players get their choice of numbers when possible, and if two players want the same number, service time is usually the determining factor.
Here's a look at how some of the D-backs players got their numbers:
Paul Goldschmidt: 44
When he got to Texas State University, Goldschmidt wanted to wear a single-digit number -- eight, he thinks -- but they were too small for him, so he wound up with No. 37.
The day he was called up to the big leagues for the first time. No. 44 was hanging in his locker.