So, 41 bowlers (post WWI) min 100 test wickets (rather than 2000 balls) - 30 had a lower average in FC than tests. Missing out were Davidson, Cummins, Bumrah, Donald, Rabada, Steyn, S.Pollock, Croft, Harris, Ashwin and Reid. Some obvious ones like Harris and Cummins, some surprises in there (Jadeja once again proving he is the goat by improving).
Ftr the other 11 batsmen who averaged more in FC were Headley, Kambli, Tendulkar, Miandad, Dravid, Ponting, Hussey, Chanderpaul, Gavaskar, Hayden and Compton.