I'm not really sure that Diego Simeone is under pressure from the clubs management, they still see him as the coach with the kind of aggressiveness that Atletico Madrid needs. His been in charge for over a decade now and seriously I don't see anyone replacing him at the moment. Some years ago, he was about to leave the team but the management convinced him to stay and till now his been there.
Actually I believe as well that Atletico board is putting a bit of pressure on Simeone and I think it started last year when his team barely produced any magic or performance but it's not only him to blame as the board didn't make any great transfers but it feels like Simeone era with Atletico Madrid is approaching the final.
Atletico for me is a synonym of a third team in La Liga. In last 10 seasons, they won one, been 2nd twice and had been 3rd the rest. There's no another name except Real Madrid, Barcelona and Atletico Madrid when it comes to top three. So, whatever the performance is, there's not really much pressure unless Atletico loses its third place. There have been some changes on Atletico I didn't liked like the departure of Angel Correa, Rodrigo De Paul and Samuel Lino all of whom had a great field presence. The offense of Atletico is still solid with Alexander Sorloth, Julian Alvarez and Antoine Griezmann but they need to work better on defense with the new players.