Walker has definitely gotten better over the last month.
I don’t think outfield defensive is as important as some make it out to be. You are talking about 300 outs per year.
In September, Walker had a game where he committed two errors (one fielding, one throwing) on one play.
He followed that up with a game where he committed an error, and they gave the other team a triple on what should have been scored a two base error.
These were games in September, after he supposedly improved in the outfield.