Debut class WAR-fare

Each new baseball season brings with it a new slate of promising rookies, full of hope and enthusiasm, who are then casually tossed into the dream-smashing furnace that is major league baseball.

This year is no different with the likes of Jose Fernandez, Aaron Hicks, and Jedd Gyorko all making their major league debuts so far in 2013. We also expect to catch our first glimpse of the very hyped trio of Wil Myers, Oscar Taveras, and Jurickson Profar at some point later this summer.

Last January, in a piece called WAR of the Ages, I looked at which age groups were hogging up their share of the WAR trough for each season dating back to 1900. As it turns out, baseball is in fact in the midst of another youth movement, but one that is really just returning the balance between youth and veterans to its previous status quo.

In a post-Moneyball world, it seems plausible to expect that teams might be opting to trust in their low-salary triple-A role players now more so than ever. Teams seem to be paying more attention to stockpiling scouting resources and expanding their scouting outreach to parts all over the globe, overall adding more and more depth to their farm systems.

And it may be more than just young prospects, too. We are also seeing some very useful, seasoned veterans of the lower leagues come up and contribute a great deal for their teams. It would seem that these older players are then promoted to the majors, wrenched of any usefulness, and then quickly discarded.

Perhaps there is a window of opportunity to exploit a debut season. That is, before the opposing team’s scouts can discover a non-prospects weaknesses, use him as much as you can, then DFA him. Repeat.

All this is wild speculation of course, but I intrigued myself enough to ask, are players in their debut season seeing more playing time than in the past? Or are they performing better than in the past?

I used data from Baseball-Reference’s super sublime WAR .csv file to query all players in their debut season in the major leagues to determine if the debut crowd is:

{exp:list_maker}1. Actually seeing more playing time than in years past?
2. Contributing more WAR than in years past? {/exp:list_maker}

As it turns out, fans were witness to one of the worst debut classes of position players in over four decades in 1993. That group, led by the disappointing efforts of David McCarty (-2.7), Darrell Whitmore (-1.7), and Phil Hiatt (-1.3), amassed a painfully low -15 WAR.

Fortunately, freshmen would rebound from that embarrassing nadir in the subsequent strike-shortened seasons, and matters have continued to improve for debut classes up until the present day. While debuting position players haven’t necessarily been given more playing time since 1993, they have certainly contributed more to the league’s overall WAR totals:


It may be too soon to tell if baseball is entering an era where the share of its WAR earned by debuting players is consistently more so than in the past. But, consider that the debut class of 2010 accounted for just over five percent of the leagues position player WAR. Only once has a debuting class come close to reaching that mark since the diluted talent pool during World War II:


The 2010 class was led by a powerhouse debut seasons from Jason Heyward and Austin Jackson (each contributing seasons totaling over five Wins), as well as impressive first rounds from Ike Davis and Giancarlo (then Mike) Stanton.

Their rivals from the 1977 debut class were led by another pair of outstanding five Win seasons from the now-forgotten Mitchell Page and Bump Wills. Interestingly, both of these first year phenoms fizzled out shortly after their rookie seasons, and neither was able to produce a career more than eight seasons in duration.

Historically, however, the current state of playing time for position player freshmen is still very near the levels it has remained at for over forty years. This is generally true for pitchers as well, with perhaps only the most marginal of increase in innings pitched beginning in the early 90s:


Debuting pitchers typically see about twice as much playing time as debuting position players. Since 1990, the debut class of pitchers has accounted for roughly 10 percent of all innings pitched, and about five percent of the WAR pie.

A Hardball Times Update
Goodbye for now.

The obvious exception to this, of course, is the very bizarre 1995 season. The arrival of Hideo Nomo to the major leagues had a lot to do with this surge, as the rookie from Osaka amassed four and a half Wins on behalf of the Los Angeles Dodgers. In addition to Nomo, however, 1995 also gave us our first glimpse of Andy Pettitte, Troy Percival, and Jason Isringhausen—all with very impressive WAR totals in their rookie campaigns. Felipe Lira and the knuckle-balling Steve Sparks also chime in with nearly three Wins a piece that season, representing the pitchers from this class that time would ultimately forget.

Certainly, pitchers in their first season in the majors have been considerably more volatile than their position player counterparts. Throughout history, both their share of the innings pitched totals and WAR totals seem to swing wildy from season to season:


Of course we’re not simply measuring baseball’s reliance on its youth from year-to-year in these charts, but rather it’s willingness to trust those players with absolutely no major league experience. Already we have a number of impact 2013 debuts from players well above what we’d typically consider prospect age a la Hyun-Jin Ryu and Atlanta’s Evan Gattis. And this current season in particular appears to be another fine one for players of their ilk.

So, let me ask you? Are debuting ballplayers becoming more relevant to the game of baseball in recent seasons? Or is this simply baseball’s notoriously ever-present randomness at work once again?

References & Resources
Thanks to Baseball Reference for the data

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9 years ago

Nice job, James. I’m wondering if the ratio of %WAR to %Playing Time is meaningful or misleading? Probably misleading, don’t you think, because of the different baselines?

Not that you used it, but it’s a ratio that suggests itself from the graphs.

By the way, a graph tip: when you have two lines in a single graph, change something more than just the color.  For instance, put the circles on just one line, not both lines.  Helps distinguish the data visually.

9 years ago

when did the MLB first allow expanded rosters in Sept?

Joe Dimino
9 years ago

There were no September call ups in 1994, I’m sure that has a lot to do with the 1995 spike.

Cliff Blau
9 years ago

MLB first allowed expanded rosters in September in 1910. Until 1968, there were expanded rosters in the first month of the season as well.