He just didn't have the backing of the board. The players knew it and didn't do all they could. What he also didn't have was the experience of managing big losses in front of the camera glare. An experienced boss just takes that on and deflects it.
A lot of the Unsworth 'failings' were perception and should easily have been neutralised.
As said, proof of the pudding is that he shifted us more places up the league than Allardyce has and he acquired more points per game.
Perception trumps reality though.