Now that Steve Smith is a member of the Baltimore Ravens, simply having "Smith" on the back of his uniform won't work. There are two wide receivers named Smith on the roster now, the other being Torrey (no relation).
Though he's young and doesn't yet have the resume of the former Carolina Panthers great, wide receiver Torrey Smith has earned the right to keep his jersey name.
With a son also named Steve, Steve Smith has elected to add "Sr" to the back of his jersey. Smith had reportedly previously announced that he would tweak his jersey to honor his son, so this may actually just kill two birds with one stone by chance and fortune.