He simply had no heart.
There was a rumour that Messier told Carson if he didn't back check he would do unspeakable physical things to Carson. Carson then demanded a trade.
The Oil sent Carson home to Detroit for Adam Graves, Joe Murphy and Petr Klima. It was an awesome trade for Edmonton.
As a side note the last I checked Carson still held the record for most goals by a teenager.
- Sabata
That was the story Pocklington's people fed the media. Not saying Carson was a saint, but Pocklington traded him because he wouldn't sign the extension (PP gave him a day to sign), and Wilbur told Carson not to.