This is all simply a matter of having MLB-capable talent in the bullpen.
During the 2020 season, Sims’ role was expanded, Antone was added, Bradley was added. The talent base was expanded. Weaker guys, like Strop, were dropped.
Iglesias was on track by appearance #3 - an unexpected talent boost since his 2019 was poor.
As the talent got better and the right guys were used, the pen did better. The same can happen in 2021 if Reds make moves to improve pen talent level.