Interesting point. Think you could attribute most of our problems against Watford to tiredness, both physically and mentally - failure to pick the right pass, losing out in tackles, failure to make the right run or any run at all....seems more likely to me than that everyone has suddenly turned to shit or was never good enough in the first place. Even lanky's point about the weakness in midfield - fresher players won't get bullied that easily.
Exatcly!
I would even dare to say that the players won't be recovering from this change in intensity quickly and Klopp will have to realise to adopt the intensity for this season only which again doesn't mean this season to be a write off. Klopp and the players will find a way, I am sure of that, as the majority are top professionals, including the manager. But you only have to look at how injuries got up in numbers, there is no way to look away from that, it's the intensity which causes the muscles to be tired and minor injuries a consequence out of that.
Kevin Keegan once was quoted that it was such a drastic change for him making the switch from british to german football as the emphasis is put so much more on training, pre seaon and regular training session compared to England where it's all about staying fresh through playing every three days.
Maybe it's not that bad but as you wrote, you cannot question the mentality of the majority of the squad, it seemed to me that they were just tired, mentally and physically, not totally shot, just tired, which is normal when a manager switches to an approach having more or less games being some sort of a light recovery session for the players after one week training... well, that's how intense a lot of training in the Bundesliga works... not that I am fan, it's just the way it is.
Just wait for next pre season.. there will be players wanting to leave afterwards..