I suggested it last season based on his appearance, lethargic/clumsy play, and the company he keeps in the offseason. Now I've heard it from someone who dated him. A tendancy to party is not unusual for young hockey players, but the ones who get that rock star personality and status in big markets are more prone to issues. See: Price, Seguin, Lupul.
It doesn't mean Matthews is addicted to drugs, that was an exaggeration, but it's a slippery slope. At the very least it can impact his conditioning and commitment. Now we've got rumours floating around about him always being the last guy on the ice at practice and the first one off. I'm seeing smoke.
When you sign that kind of contract you subject yourself to speculation. I hope he shows up looking healthy and refreshed and puts my mind at ease. Maybe it was just a big summer after his 60 goal Hart season.