by Geoffrey MillerFiled under: Dale Earnhardt Jr., Sprint CupSaturday night's Coke Zero 400 at Daytona will mark the official midway point of the 2009 NASCAR Sprint Cup season. Naturally, it's a great time to review what we've seen so far from the Cup boys, their teams, the series and the tracks. First, we'll start with the not-so-hot performers:Motorsports FanHouse Grade: FDale Earnhardt Jr. - It's been easy to see why the season for driver No. 88 has earned a failing gra...