Top CA state income tax rate is 13.3%, but about 3/8 of his ball games would be played out of state. He'll get W-2's in every state in which he plays games, so he would file at the lower rate in those states. So he'd pay no tax in Texas, Washington, or Florida, and just 3.07% for Phillies and Pirates games. 42 states have state income taxes. Lowest is Pennsylvania (hello, Phillies and Pirates!) at 3.07%, but then you have to live in Pennsylvania...California is a dream for most people. BTW, of the eight states that don't tax income, most are in the West: Alaska, Wyoming, Nevada, Washington. Others are Florida, Tennessee, Texas, and South Dakota.
Audaces fortuna iuvat