All fair questions. The alleged crimes here against the Adidas Exec. are wire fraud, money laundering conspiracies (the Victim(s) are the schools, believe it or not).
The alleged crimes here against the coaches are primarily wire fraud, wire fraud conspiracies, and solicitation of bribes, and bribery conspiracies. the victims are various in these instances.
There's always a question of resource allocation when it comes to any investigative body (DOJ, FBI, local law enforcement, etc. etc.) that card can be played at any time on any issue. Ex. I bet you guys don't know this, but just about every US Atty's office in the country has an AUSA who's primary job is to go after people who are not paying back the federal government (student loans), in a civil (non-criminal nature). Great use of resources? Maybe, maybe not, but the Gov't has a lot of resources, though not infinite, and initiatives, and at times are earmarked funds to undertake certain initiatives and lots of interests to protect. When I worked in a US Attys office for a summer I worked on all kinds of civil and criminal matters. It's not all glamorous stuff.
This case appears to have been generated by sources who came to the government, which in turn used informants to gather further evidence.