Pitch
Someone I knew very well died in a similar accident to this one. The report found that prior to rolling inverted the pitch up was less than intended (due to a hazy horizon over the sea) which dictated entry altitude and thus left him with insufficient room to pull thorugh as intended.
He was very experienced indeed and had been a member of that famous jet aerobatic team. Even the best of us can get caught out on the day and at low level, mistakes carry a heavy penalty.