The Ellie McDoodle Diaries: Most Valuable Player by Ruth McNally Barshaw
Poor Ellie. When her best friend, Mo, suggests they try out for football together, Ellie isn't convinced she's the athletic type. And sure enough, Ellie can't seem to get her head (or her feet) around the game, even with her dad's help. The truth is, Ellie would much rather be doing brain-bending puzzles with her school's Journey of the Mind club. But when both teams have a tournament on the same day, the race is on to see whether Ellie can be in two places at once and help her teammates bring home a win - on and off the field!