Here is another suggestion. Supplement the draw rule by 10 moves (20 plies) - or some other amount - at agreed zero score regardless of pawn moves or captures.

Here is a different modest suggestion.

Some engines move instantly without posting a position evaluation. In some games this resets the TCEC win or draw rules. I think there was one game in stage 1 where an engine lost on time or by stalling after the win rule was reset in this way.

If the engine ...

It was suggested that I should post my analysis of Stage 3 by quarters - which shows some striking variability in performance:

Q1: Komodo +3; Houdini, Stockfish +2; Critter +1; Gull, Rybka =; Fire, Shredder -4
Q2: Stockfish +4; Komodo +3; Houdini +2; Fire =; Critter, Rybka -1; Gull -2; Shredder -5 ...