Agreed, it sounds like he may have changed. This post from Bigfooty gives a decent insight into what he may have gone through after being drafted
"Thorp is one who merely struggled to make the transition to the relentless nature of the afl system. For those of you who don't know his background, Mitch grew up in a very small town in Tasmania and had very little experience with what he faced when he first moved to Melbourne.
He always had an air of self-confidence about him, but I wouldn't say he was overly egotistical. From a very early age he was a very driven character, working extremely hard at his football. The amount of training AFL Tasmania subjected his body to ultimately led to his injury problems during his time at Hawthorn. Right up until the day he was drafted I had never seen him touch a drop of alcohol.
Clearly things changed dramatically after he was drafted, leading to the aforementioned gambling problems. However his biggest problem was a battle with severe depression and anxiety, surprisingly caused by the weight of expectations from the outside world (doesn't seem too egotistical to me). This led to chronic insomnia, which saw him be heavilly medicated.
Now I'm not saying that he didn't have his faults, but the story is much deeper than what is commonly reported. From my brief encounters with him over the past two months I can confidently say that he is in a much better place than he was prior to his delisting at Hawthorn.
The drive is still very much there and his injury troubles are merely a thing of the past. I think he could be a very valuable addition to any club, but I'm not certain he will get the chance.
Give him a chance fellas, if Tim Harrington believes he can add some value to your side, then surely that is enough?"