Why do good teams look shaky at beginning?

Why do some of the teams who normally do well (e.g. PRX, FNC) start the year a lil shaky? They do well at the end of the year before and then don't look as good the beginning of the next.
Is there a reason for this? Do they take some time to adjust to new metas or fall out of the rhythm or something? Just wondering if anyone has any ideas :)

EG always starts shaky we're gonna be better after kickoff tho

Fr TS also looks shaky but their gonna pop off later fs

late bloomer

prx known to be awful every meta changes ever since something joined though