4) Austin Nola as the starting catcher never clicked from day one
Austin Nola beginning the year as the Padres number one catcher wasn't quite as indefensible as some of the other decisions the front office made, but sticking with him as long as they did wasn't ideal.
Nola was never the best hitter but was a solid defender behind the dish. This season, he provided nothing. First, as a hitter, he was brutal. He slashed .146/.260/.192 with one home run and eight RBI in 154 plate appearances. A .452 OPS is simply unacceptable for a guy who was the team's primary catcher for the first two months of the season.
His defense wasn't much better, unfortunately. He was in the 31st percentile in pitch framing according to Baseball Savant, costing his team three runs. He also threw out just 17% of would-be base stealers. Not great.
The Padres added Gary Sanchez later in the year and he was a major upgrade. Even Luis Campusano turned it on at the end of the season and looked like the top prospect Padres fans had been waiting for. Pretty much anyone the Padres threw behind the dish was an upgrade over Austin Nola, and that's a problem when he was the starter for one-third of the season.