50 games is pretty severe, but the penalty should be severe.
Doing a quick search online, it looks like possession of steroids is punishable up to 1 year in prison for a first time offense, per federal law. In some states, its 5 years (louisiana is one). If you have the intent to distribute, say, by creating a website whereby anyone, including MLB officials, can buy the drug, the penalty goes up quite a bit. I dont think his true intent was to distribute, but I could see the state making that argument persuasively.
Just think about the poor Yankees, who not only paid Melky when he sucked, but also lost a home game in the 2012 world series because of him.