Goyf fits what this deck wants perfectly, be a clock that kills the opponent quickly as you naturally cantrip and disrupt your opponent. He is harder to put down, but is critical in a bunch of matchups you cant pretend have been handed over to delver. He is exceptional in the mirror, UR delver, and against random decks.

The reason why other decks have dropped him isn't because he isn't big enough anymore. No, it is because he offers zero utility. A perfect example of this is maverick, who doesn't care so much about spot removal since every creature can both attack and provide disruption.

But that isn't what this deck wants. It wants a clock behind its wall of soft counters and burn. Currently the best 3 creatures for it are Goose (for control), delver (creature/combo), and goyf (creature/combo). Is he the best? No. But he is still unconditionally big most games, and that is all we care about