If the worst thing he's doing is smoking some weed, then he really just needs to learn to stop failing drug tests, which I assume are gonna get more frequent after multiple failures.
My concern is that smoking weed isn't the worst thing he's doing, it's just what he's getting caught for. Or that it's symptomatic of general personality/attitude issues.
This is going to hurt his free agent stock, especially if there are rumors about worse stuff floating around. From a purely team-centered perspective, that might mean we could nab him for the MLE, which is an underpay for his talent. But the downside is the possible effects of signing up a problem player, who's alienated at least one and probably both teams he's played for. I know he's from the Boston area, but that could either be stabilizing or put him around any bad influences from his past. Either way, I hope he turns his career around, it looks a whole lot less rosy than it did 2-3 years ago.