The suspension is the result of a missed drug test, not a failed one, sources said. The reason it hasn't been announced is that the appeal process is ongoing.
No date for Bell's appeal has been set, although it's expected that it will be heard before the regular season. If it's not overturned, he would miss the first four games of the season.
According to the league, missing a test is the same as failing it. As the article notes, Bell is appealing the decision, so it could be overturned, but there's a good chance that he misses the first four games of the season. This would seriously hurt his draft stock while boosting the stock of his backup, DeAngelo Williams. Williams averaged 21.3 touches for 112 yards and 1.1 touchdowns in the 10 games that Bell missed last season. Williams is 33, so owners should not expect that sort of production again, though he should be a serviceable RB2 as long as Bell is out. After his ban was reduced to two games last season, Bell's ADP remained in the early 1st round, though a four-game suspension is a lot tougher to swallow. We expect he'll fall out of the 1st round, while Williams' ADP will rise a few rounds. The silver lining here is that Bell has an extra month to recover from MCL and PCL surgery, so he should be good to go in October.