We can't really use it as a point to think that maresca will help chelsea to compete for the big six since the early of season. Do you remember what kompany did before? He brought burnley to the EPL but it goes down again. Chelsea has so many bad stories with various coaches like potter.
Im still doubting maresca's competence for this job considering the pressure from chelsea's owner is very big at this moment. Pochettino has built up the squad and maresca can still continue this.
The better for him to do a minor change for the club. The bad things if chelsea aimed to sell some of important players like gallather or even chalobach which were performing consistently last season.
Of course, there is no guarantee that Maresca will bring big impact for the improvement on Chelsea performance. Chelsea is not an easy team to manage, there are already too many coaches failed to manage Chelsea. I think Chelsea is a bit similar with Man United, this team is no longer as top teams anymore. In the last 2 seasons, Chelsea always finished the season out of the top 5.
Pochettino has done a good job, he can improve Chelsea position in the EPL standings.