I'm not agree with your statement, as LFC fans, they only lost focus for a while, maybe they underestimated Watford...
I wouldn't blame this loss to Watford based on loss of focus, it's almost impossible to play 38 games and not lose at least one out of them all, Liverpool didn't lose till this past weekend against Watford and that's an incredible feat for them, the loss was bound to come and it definitely was going to raise questions and complaints, but imo there should not be any, they already have the Epl as theirs.
For the Liverpool fans, I just hope this loss doesn't open the door for more defeats, most times losing after so long a time of not doing so can have a negative effect on the team, if they fail to win their next Epl game, they could end up losing close to three games before the end of the season, well it will change nothing.