In the movie, multiple people made reference to him being less competent, changed, worse in some way.
But, he was generally very competent throughout the movie, fighting aliens, finding useful allies to help them solve problems, and the only times he failed was in a fist fight vs an alien and other times when his fellow (not changed) Tessa Thompson also failed. He didn't drunkenly forget what he was doing or get distracted while seducing someone.
So, what was the movie trying to say had changed about him? What was his actual incompetence or failure that the big blue alien detected in him that was not present in Tessa? I've heard about script rewrites, was he less competent in other script versions or something?