That he's been thrust into a spot -- and that he's taken on that spot -- where it invites fatigue from the fan base. That's natural when the one voice on so many things is the same voice. The same phrases don't resonate like they once did. The same jokes don't play the 12th time you've heard them. Tony La Russa talked a lot about the 10-year limit on his message, and whether after 10 years the clubhouse tuned him out because they knew all his phrases, knew all his ways to motivate, and what once worked now was just tiresome. Mozeliak wanted to move into a different role as president of baseball operations, but this past year has thrust him back into the spotlight as the spokesman in a year, had it been normal, when Girsch likely would have been more front and center on the roster. That was the idea. Then a pandemic came. Then Mozeliak deputized himself as in charge of the COVID response, and then an outbreak happened, and Mozeliak was the forward face of the organization. A year ago, at the Winter Meetings, it was Girsch that spoke to the media more often than Mozeliak -- or at least as often. Not so in the past few months, and that has definitely added to what you're describing.
It's something that is true in other realms, too. As a writer who has covered the team now since 2004, I have to be aware of reader fatigue, too. Same phrases. Same way to cover the thing. Revisiting same themes, telling the same story, droning on and on and on about the same stuff -- that can tune readers out, just like it does fans.