The presence of Buschwhackers is seen as problematic by some regulars in the lower series, who complain about more accomplished Cup drivers taking the top prize money and thus leading to loss of sponsorship for their efforts. Cup drivers often run in cars fielded by or affiliated with their Cup Series teams, giving them superior equipment and increased resources. The presence of the Cup teams have driven up the costs of competition, forcing many independent Xfinity Series teams to shut their doors. Many sponsors are hesitant to put financial backing behind an unproven driver, insisting that Cup drivers run in at least part of the schedule, which has led to several incidents of young drivers receiving part-time schedules or being pulled from an entry before (or even during) a race in favor of a Cup driver. In 2008, for example, Kelly Bires was forced to sit out the Daytona season opener due to contractual obligations with JR Motorsports' sponsor Unilever stating that Dale Earnhardt Jr. drive a certain number of races for the team. Other criticisms of "buschwacking" cite the lack of Xfinity Series veterans left in the series. Long-time series regulars and champions (such as Steve Grissom, David Green, Randy LaJoie, Jason Keller, Casey Atwood, and Ashton Lewis, Jr.) have seen their exit from the series in the 2000s, while 2000 champion Jeff Green has driven primarily in start and park entries since 2011.