In the Kevin Costner baseball movie Bull Durham (1987), it was said you don't mess with winning, you don't mess with a winning streak.
At Manly, we have always done much better with one of our own in charge. All 8 of our premiership wins have come with former Manly players as the coach. Ron Willey, Frank Stanton, Bob Fulton and Des Hasler. And while not winning the premiership, we made Grand Finals with former Manly players such as Arko, George Hunter, Ray Ritchie and Tooves as coach. To my recollection, the only 'outsider' who even came close to having coaching success at Manly was Graham Lowe, and as good a coach as he was we still never even made a GF under him.
All Trent Barrett proved as Manly coach was that he was out of his depth as a first grade head coach. And by quitting the way he did, especially with all his whinging in the media, I think he did a lot more harm to his reputation than he would have had he stuck it out to the end. Right now I seriously doubt if any NRL club would want him as their coach. Even the Titans would go for someone like Tooves before they considered Barrett.
And to this day I still believe that Phil Gould sold Barrett's virtues as a coach to Bozo more just to get him away from Penrith than because he actually believed what he was telling everyone that Barrett would become a good coach. Seriously, if Gould really believed what he was saying, he wouldn't have gotten him away from their U/20's at the first opportunity and he would have had him lined up as Penrith coach knowing that he was going to sack Ivan Cleary rather than trying to get him away from the club.