The media love to paint stories, and stories are full of strong characters, heroes and villains. As an example of the subtle (and often not-so-subtle) brainwashing and stereotyping used to build club caricatures, it is interesting to note how we are always painted in darker tones with repetitive use of the words such as 'ominous', 'machine' and 'relentless' by multiple writers whenever it looks as if we have an advantage in anything. Articles about how to beat the relentless ominous Chelsea machine seem to go hand in hand with our successes.
I think it stems from the negative football players last season, Chelsea under Mourinho are at times a very defensive team and very difficult to break down. The introduction of Costa and Fabregas means you are now more expansive but still strong in defence. I would take it as a compliment.
Pretty weird of the Media to introduce "darkness" to the Chelsea description. Looks like the lights are on to me, and everyone's home !!