2015 Gibby was borderline Montoyo. Not full Montoyo, because no one is that stupid, but in a similar category. Had no idea who his best relievers were, defensive lineups were bad (pre trade deadline), and the team at the deadline was .500 with a huge positive RD, multiple MVP candidates, etc. The division was much weaker that year so they were able to win the division with their 2nd half run. The 2021 team is in the most stacked division in the league so their 2nd half run is likely going to fall short.
Definitely some revisionism with Gibby, but in 2016-18 I thought he was a perfectly competent manager, and really that's all the team needed in 2021. Put Gibby on this team this season and it's leading the WC right now. No question in my mind. But they could definitely do better, and the job is much more appealing now than it was when Buntoyo was hired.