Starters aren't the only ones pitching fewer innings

During February there is rarely a great deal of major MLB news, but one of the biggest stories right now is the continued unemployment of James Shields. Whether one defines Shields as a "true ace" or dismisses the importance of that moniker, it's abundantly clear that he is an excellent pitcher.

The 33-year-old has produced a 3+ WAR season in seven of the last eight years and would be a useful contributor to any rotation, perhaps with the exception of the Washington Nationals super staff. While there's an argument to be made that his calling card is his changeup or command, the reality is that above all Shields is known as a workhorse.

Over the last four seasons Shields has 932.2 innings pitched to his name, the highest total in the league by almost twenty innings. That total is impressive in an era where pitchers are not working as deep into games as they have in years past. The term "workhorse" used to describe Shields is a relative one, as he excels compared to his direct peers, but in the context of baseball history his innings totals are not particularly outstanding.

However, phrases like "workhorse" are bound to change with the times, and there's no better way to judge a players performance than by comparing him to his contemporaries. It's common knowledge that pitchers just aren't piling up the innings totals of their predecessors, but what exactly does that look like?

As it turns out, over the past 50 years there has been a moderate decline in the number of 200 inning starters, but it's mainly the higher totals that are becoming unattainable.

It has become incredibly rare for starters to throw 250 innings, and 300 innings pitched in a season may be a thing of the past barring some kind of breakthrough in keeping pitchers healthy or replacing them with cyborgs.

None of what appears on this chart comes as a surprise to most baseball fans. The decline in starters' workloads in recent years has been well documented and often moaned about.

What has been less discussed is the decline in relievers putting together seasons with high innings totals. The idea of a 100 inning reliever is intriguing - especially as a role for oft-injured starters/Tim Lincecum - but there hasn't been one since the Yankees' squeezed 102.1 frames out of Scott Proctor in 2006.

Even if the benchmark is reduced to a very attainable 75 innings fewer and fewer relievers have managed it in recent years.

The drop off in the last five years is particularly noticeable. In order to avoid swingman confusion I've included only players that pitched 100% of their innings in relief in the chart above. That led to some omissions, but it kept the waters from being muddied. All the players here were seen by their teams exclusively as relievers and deployed as such.

Bullpen specialization has been blamed for baseball's offensive downturn, slowing pace, and the dreaded strikeout scourge, and it is a player in all of these trends. Another of its effects is creating a climate where individual relievers aren't putting up the kind of innings totals they have in the past.

As teams try different methods of keeping their prize arms healthy it's possible that could change, but for now the definition of a workhorse reliever is changing by the season, just like it is for starters.

The only difference is it's doing so more quietly.

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All statistics courtesy of Baseball-Reference

Nick Ashbourne is an Editor for Beyond the Box Score. You can follow him on Twitter at @Nick_Ashbourne.