His knowledge of players at every level of the game was unreal. At the sponsors do a few years ago, Gary Harkins told me Hartley was always first in to Dens every morning and last to leave at night, incredible number of hours he devoted to the club.
His downfall in my opinion was his stubbornness bordering on arrogance. Very rarely held his hands up and admitted HE got it wrong, more often than not it was the players' fault. This led to him sticking with set-ups and strategies that clearly weren't working, until the point that they worked, which is why we had so many horrendous runs of defeats on the bounce. He always struck me as someone who would persist with a run of defeats if it meant his game-plan working just once, so that he can say "see, it worked."