Greg Holland had a solid season returning from Tommy John surgery, undergone in October of 2016, posting a 3.61 ERA in 57.1 innings as the Rockies closer in 2017. He also picked up forty-one saves in forty-five chances, good for the fifth best save percentage in the majors. With how the season went, the St. Louis Cardinals are looking for any back-end help.
More than anything, the Cardinals need reliability, availability, and consistency in the bullpen. Holland has proven reliable with a career 2.72 ERA over his career. He has had a pretty clean injury history besides his aforementioned surgery, and small, weird, nagging injuries.