I always believed that a combination of Tim Howard (who left 3 seasons too late) and the board going after Funes Mori at £6.5m when Van Dijk was Roberto's first choice at £11m.
We ended up getting screwed for £9.5m in the end. Typical Everton of that era. An actual Premier League goalkeeper and Van Dijk/Stones as centre halves and Roberto would still be in charge.
That was Martinez’s fault.