It’s a bit of an obvious statement that bad teams don’t need good bullpens. That bears itself out pretty well if you look at the standings and the bullpen ranks: of the top 10 bullpens by fWAR in 2017, six of them are taken up by playoff teams. To that end, it’s not surprising that the Braves finished the season with the league’s fourth-worst bullpen by fWAR (fifth-worst by RA9-WAR).
The Braves only used 19 relievers in 2017. That’s actually perhaps a bit surprising, given that they used 26 in 2016, and 33 different relievers in 2015.