Unwinding the wage bill
The immediate problem after relegation is financial, and it arrives faster than the sporting one. Contracts written on the assumption of top-flight income become unaffordable, and clubs that planned for the possibility — with relegation clauses, sensible contract lengths and a wage ceiling that never assumed permanence — get through the summer intact. Clubs that did not are forced into sales at bad prices, which weakens the squad exactly when it needs strengthening.
This is why the quality of a club's administration is most visible in its worst season. The decisions that decide a relegation summer were taken two years earlier.
Who to keep is harder than who to sign
The instinct is to retain experience, and some of that instinct is right: a dressing room needs players who can steady it. But a senior professional who is unhappy at the level, out of contract soon, and clearly waiting for an exit does more damage than his replacement's inexperience would. Every relegated squad contains a few of those, and identifying them honestly is unpleasant work that clubs frequently postpone.
The players worth fighting for are usually not the biggest names but the ones whose game translates: defenders who win duels, midfielders who can play under physical pressure, forwards who score from ordinary situations.
Coach for this division
Relegated clubs often appoint a coach whose reputation was built one level up, on the theory that the club is really a top-flight club having a bad year. Second-tier football has its own demands — managing a congested fixture list, winning ugly matches in February, keeping a squad convinced through a run of draws — and coaches with a record of doing precisely that are usually available and less fashionable.
The best test of a rebuild is not the first six weeks but the response to the first bad month. Squads assembled with the division in mind tend to have an answer; squads assembled out of pride tend to have an excuse.