Ross is not a terrible manager. He's also not a championship manager or the manager of a team that has aspirations of the playoffs. He's a Rick Renteria-type manager. He gets the team to play hard, but he's deficient in the strategy needed to be a good manager. He may have been able to learn it as a bench coach, but he's never been a bench coach.
Every couple of days we see his deficiency on display in a winable game that the Cubs lose or a game that got away before he did anything about it.
I don't think he's going to get fired until they put better players on the team and they stall out.
I don't think this team has the same talent level as the 2003 team, but a similar phenomenon is happening. They're out of gas.