With the way this team is constructed (which, that's a whole other argument) they need to be able to win on the margins, and it just hasn't happened. Ross has seemingly not trusted enough guys early, leading to large workloads for guys with injury history like Alzolay and Fulmer and someone who has never faced a relief workload like this in Leiter Jr., and trusted guys like Cuas just because. Batting order doesn't matter a ton, but it seems to me that guys in horrible slumps (Happ earlier this year, Swanson now) have gotten way more ABs high in the order than their performance deserved.
Anecdotally, it also seems like he has been too slow to react to his pitchers losing it, not having guys up when a starter is running out of gas, not getting guys up when pen arms clearly don't have it on a given night, etc.