Jordan Walden was a not insignificant part of the Heyward trade. With Miller shipping out, Carlos Martinez could move from the bullpen to the rotation. But getting Walden back helped make sure that the bullpen would stay strong without Carlos as a late inning/high leverage reliever.
Things didn't work out that way though. Walden ended up throwing just over ten innings in 2014, and the Cardinals went into the off-season with expectations for Walden that were similar to the same expectations Jaime Garcia had last year. No one can deny the talent when healthy, but it would just be foolish to depend on seeing that talent on the mound much. Better to just assume he's not a part of the bullpen, and be pleasantly surprised if he ends up healthy.
John Mozeliak and company acted on those expectations and shored up the pen. With the signing of Jonathon Broxton and Seung-Hwan Oh, and the likely move of Tyler Lyons to the pen, it looks like the pen will be fine without Walden. With Spring training getting under way, there has been news that Walden claims his shoulder healthy, combined with him participating in all the same Spring Training activities that all the other pitchers go through, there remains a real chance that he can contribute at a high level again in 2016.
Were Walden to be healthy, it would probably give the Cardinals one of the best bullpens they've had in a long time. So I wanted to look at best bullpens in Cardinals history. Of course, bullpen use has evolved a lot over the years, but WAR at least let's us know which were best with the opportunities they were given:
Its interesting to see how these stats change over time. 2004 and 1995 remain the best years in terms of WAR among Cardinals bullpens, but 2015 and 2013 are both right behind them. The 1930 season is a bit of an aberration, as even though I selected the "reliever" tab on fangraphs to control for only bullpen innings, the stats still include 30 starts in there. I wanted to leave them in though, just to see those crazy strikeout and walk numbers from that year. Baseball sure has changed a lot over the years.
I think the this year's pen can definitely be an improvement over 2015 and 2013, so being one of the best appears to be within reach. Lets look at what the projections think, first from Fangraphs' Steamer-based depth charts:
Steamer still lacks a projection for Oh. Taking the best eight options not including Oh, weighted based on how the Fangraphs' writers think innings will be split up, results in a FIP of 3.39, which would improve upon 2015's 3.50 number. These 8 meeting their projection would put them 6th in WAR among Cardinals' bullpens, but that's also just a total of 390 innings, which would be a meager total in this day and age for a bullpen. Give Oh 50 or 60 innings and we're around the amount of workload a modern bullpen gets. Let's also see ZiPs:
ZiPs doesn't make decisions about how playing time is dispersed, so I can't make a similarly weighted FIP stat for this projection. However, ZiPs does consider most of the Cardinals' relievers better than Steamer does. ZiPs also has a projection for Oh, set at 3.40.
Now, there's a lot of variance involved in bullpen performance. That's why we can't assume the Cardinals bullpen will even be good this year. Disaster could strike in form of a few pitchers getting hurt and a few more under-performing. But there's a chance for over-performance as well, due to the same variance involved. With good health and a pitcher or two pitching above their projections, and the 2016 Cardinals bullpen could very well end up being the best in franchise history.