While it's true that SPG is usually steals per game, I somehow don't think that's what was being conveyed in that panel. She's talking about becoming a regular on the team, so wouldn't the coach be calling out the position and then her name to signify her getting it? So in this instance it's probably a shooting guard shortened as SG or maybe a combo guard which they decided to put as SPG (shooting point guard?). I guess I could be wrong, but seeing the credit notes at the end made that panel make less sense for me, not more.