Sam LeCure had a rough season last year. He pitched in 62 games and posted a 3.81 ERA. That isn't great, but keep in mind the quality of the season for the whole team last year. It wasn't good.
The last time the Reds had a good year as a team, LeCure pitched in 61 games with an ERA of 2.66. That was 2013, just one season before last year's full team collapse.
Let's compare that to Kevin Gregg, Bryan Price's new favorite reliever who sent Sam to the minor leagues. The lowest season ERA Gregg has ever posted was in his debut year (2003) with the Angels. He did well and earned an ERA of 3.28. But that was only in 5 games. The very next year, Gregg posted a 4.21 in 55 games for the same team. The lowest ERA Gregg has ever earned in a season where he pitched more than 20 games was 2008 with a 3.41 ERA. Gregg's highest ERA season with 20+ games resulted in an ERA of 5.04. Basically, Gregg has never, in the 12 years he has played, been a decent reliever.
Look at Sam LeCure. He is 30 years old, had a single bad season last year, and still sports a career 3.53 ERA. Why did Gregg get picked up and why did LeCure get sent down?