Did you read the article? it wasn't digital files, it was the actual Cards.....
No, I was working.
And instead of attacking the person who has the cards, who has no ability to obtain them himself -- unless they think he broke into the building, which no one appears to believe -- going after him is an incredibly stupid way to do it.
He has no ability to cause this to happen again and going after him in a predictably Pinkerton fashion is going to just result in him blabbing about it on social media, as happened.
The Pinkertons are
not just any old private investigators. They're famously thugs. Anyone who's heard of their brand should know that.
If you reach out to him, go with a soft approach, appealing to his love of the game and the brand, offer him a bunch of swag and work up to getting the fan to "understand" that leaks are bad for the brand overall and seeing if he'd flip on his source. (Even then, checking his social media connections is a lot better way to do that and wouldn't tip him off that he's being investigated.)
So, how do you prevent future leaks without knowing how you're currently leaking?
This was a stunningly stupid way to do it and it predictably blew up in WotC's collective face (again).
But since you asked: You start with creating a list of who had access to the cards, figuring out where this particular batch came from and at what point it could have left the building. All of which could be done in-house (with or without thugs) and which would actually address the disease, not the symptoms.
I get you all have an automatic dislike for WotC.
Not me. I have an automatic dislike for stupid and short-sighted actions, though.