This is skirting around the issue, though. The NFL had the tape already, and at best there was nothing standing in the way of any modest investigation turning it up. The NFL made a lenient ruling because it wasn't a big deal to the media, even though the evidence was right in front of them. NFL changes it's ruling only because it got caught red-handed for not actually investigating or applying appropriate punishment.
The Suh situation could very well be the same. There is blatant evidence (contract details released prior to the open negotiation period) that is being ignored or actively not researched (just like the Rice tape). If the media were to suddenly turn the glare on the obvious tampering that goes on (likely with regularity) in the NFL, suddenly there would be more thorough investigations and heavier penalties.
The NFL is not a proactive league. Most large, successful institutions aren't. The fact is, they don't want anything to change. They don't want to spend money on investigations, pensions, health research, or even proper referees. It's only when they think these things could hurt their bottom line (media driving away fans) that they do much of anything. Honestly, would the NFL even be testing for PEDs if it weren't for the cultural taboo over them?