Cobb's second fumble

What i am confused about is that the whistle blew before the Sask player touched the ball. I agree Cobb was not down when he fumbled but as soon as the whistle blew with the ball laying on the ground should it not have been a dead ball and therefore should it not have been Hamilton's ball.

From the CFL 2010 Rulebook:

[b]REVIEWABLE PLAYS - GUIDING PRINCIPLES[/b] The instant replay system will cover a variety of plays in three main areas: ... 3. other detectable situations, such as a ball carrier ruled down by contact, and a fumble which occurred prior to down by contact ... [b]APPROVED RULINGS Running Plays[/b] A.R. Fumble before runner down by contact Team A ball carrier fumbles the ball with Team B recovering. Officials rule down by contact at A’s 30 yard line. Replay shows that the ball was loose before the runner was down. RULING Reviewable play. [i]B’s ball at point of recovery with no advance.[/i]
There have been statements concerning calls in recent games that the fumble recovery must be immediate. Basically, if players stop playing because they hear the whistle, and then a player decides to pick up the ball, it's not considered a fumble. In this case, the 'Riders player chased down the loose ball right away, so it was deemed to have been recovered immediately.