Why pay a premium for Leicester City defender Harry Maguire rather than go for Ajax captain Matthijs de Ligt?
Why is manager Jurgen Klopp trusting his Liverpool team to maintain last season's momentum rather than investing in foreign talent?
A new academic study may have the answers.
Researchers at University of Manchester have crunched the data to reveal how long it takes players arriving in the Premier League from other European leagues to find their form.
They looked back at in-depth performance data spanning several seasons for players moving between the continent's six top leagues. For each player they assessed how those indicators were affected by their transfer to a new club.
The bad news for forwards from Dutch and French clubs is that they took the longest to adjust, playing an average of 18 games before they reached their previous level.
Striker Afonso Alves, who struggled after arriving at Middlesbrough from Heerenveen in 2008, or Radamel Falcao, underwhelming during loan spells at Manchester United and Chelsea from Monaco, might sympathise.
The quickest to adapt to life in the English top-flight were midfielders from German clubs and defenders from Spanish clubs, who replicated the form that attracted a Premier League buyer almost instantly.
Players transferred between Premier League clubs needed little time to adapt to their new surroundings with no adjustment period for defenders, and midfielders and forwards taking an average of three games to recover their form fully.
Number of matches to adjust for players transferring to Premier League clubs from:
Other Premier League clubs