Another question I have is when were the tests administered? Was it after the regular season in advance of the bowl game? Do they test before/during the season? If it's more likely to happen after the season but before the bowl, you will probably see players like Dexter Lawrence take a pass on the bowl game - kid was likely a first round pick (and still may be) but why risk it? Now he's a drug user.
Impossible to say. Drug testing is by plan. Not all teams and not all players are tested during the season. Testing is suppose to be more extensive in connection with (NCAA championships and) post-season bowls, but, again, it's not universal.