At the beginning of the season they performed a little better in Serie-A and they got a much more convincing game pattern. But in the last six games Fiorentina started to struggle to develop their game and even struggled to get wins. The quality of the players they have is not as good as some of the top teams in Serie-A and maybe that is what needs to be improved so that they can compete with the top teams in the next season. The focus now is to finish the League in the top five so that their motivation in the next season will be much greater and that is not easy because they need to show consistency so as not to lose many more points in the next match.
Fiorentina decline started in their last 6 or 7 games just as you have said, earlier on in the season, they were doing well but declined all of a sudden, maybe their squad depth isn't enough to stay at the very top in which they had planned to, maybe fatigue has set in for the players and they are tired that's why they have this sudden decline in form which has been affecting their recent run of form.
If we look at Fiorentina's recent match performances, they lost to Monza and Napoli. They drew with Juventus, lost to Udinese and drew with Guimares. Before that, they lost to Bologna. They haven't won in the last six matches, including the Europa League and Serie A. Now they want to put an end to this misfortune. I thought they would win against Monza, but they really lost that match as a big surprise. I don't know what Fiorentina did wrong, maybe they are going through a stressful period.
Fiorentina's woes started when they lost 1-0 against Bologna on match day 15 since they have not won any game so far, out 5 league games they've played lately, they have lost four and drawn one which means out of possible 15 points they were only able to get one point which was the 2-2 draw against Juventus and lost 14 points. That's a real poor run in form. Perhaps they are going through a stressful period just like you stated earlier on.