Bullpen obviously didn't work out as intended. I'm sure a lot of us (me included) thought that Pressly/Abreu/Hader was gonna be a lockdown back end. Figured we'd rarely ever drop games if leading late. All 3 recorded ERA over 3.0 and took a combined 16 losses.
OF was a mess. Jake and Chas combined for a whopping 1.1 WAR over 700+ AB. Our one good true OF started out playing like an MVP and then a freak injury cost him the entire Summer, and he's still obviously not back up to snuff. We had to give several hundred additional AB to cast-offs or prospects not ready for primetime (Cabbage, Gamel, Heyward, Loperfido, Leon).
Yordan's knee decided to crap out just in time for the playoffs.
1B was such a black hole for the first 2 months of the season that Singleton filling in with 0.3 WAR and .700 OPS was a massive upgrade.
Starting pitching was really the one surprise strength, given how many innings had to be pitched by rookies, and the fact that 4 or 5 guys we figured would feature heavily either barely contributed or missed the entire season.
Got a lot of work to do in the offseason. Get a real 1B, get a real CF, upgrade 1B, replace Bregman somehow.