Defining rotation slots in terms of WAR

As we watch prospects begin to develop or see new players acquired via trade or free agency, everyone is always quick to classify a starting pitcher into a spot in the rotation. We hear things like "He projects to be a low-end No. 2 or high-end No. 3 starter" or "He's an ace." But what exactly does that mean? I decided to do a small bit of research to see what the spots in the rotation actually look like.

The Baseball Reference Play Index Tool is an amazingly useful tool whenever you feel the need to dork out and immerse yourself in numbers. It requires a subscription, but it's well worth it. For my study, I used the tool to gather data from 2000-2013 in a quest to find out what exactly an ace pitcher looks like.

To put a qualifier on the data, I filtered to only pull pitchers who qualified for the ERA title, which means they pitched at least 162 innings in the season. This basically gave me a group of pitchers that pitched the entire year. They may have missed a few starts here or there, but for the most part it weeds out guys who either split time between the pen and the rotation as well as guys who either got hurt or were replaced due to inefficiency. To make this list, you really had to be a starter all season long.

If you're like me, you feel a little frustration when your team can't keep five consistent starters in the rotation all season. If you've been reading my View From the Bleachers blog at all over the last 10 years, I make no secret that I hate bullpens with a passion and believe strongly in filling them with guys from your system and spending money on other components of the team. However, how feasible is that request when it comes to the rotation? I was a little surprised by what I found. Looking at the chart to the right, you will see the number of players who pitched at least 162 innings in each season.

Not surprisingly, there aren't enough guys who can give you 162-plus innings to fill out each rotation in baseball. Over the last 14 seasons, the average number of guys who met the requirement per season was 87. That's less than three per team. Stop and think about that for a second. What's even more insane is that we know that the pitchers are not distributed equally, which means there is the potential that a team could have no pitchers who meet the requirements. There simply isn't enough talent or enough healthy pitchers out there.

Now that we have the knowledge that there aren’t enough quality starters to go around, we have to figure out a good way to then classify pitchers. Seeing that we don’t have enough guys to simply take the top 30 and call them aces and downward through 150, I decided to divide the average number of qualifiers by five, the number of spots in a rotation, and group guys into one of those five tiers. What I got in terms of results was actually quite nice.

For sorting purposes, I ranked players by WAR, which summarizes nicely into a single number that matches up well to Cy Young/MVP voting. Generally the higher WAR guys tend to be right in the mix for those awards, so it seemed the most logical stat to use. After taking all the results, I organized it into a summary that showed the average WAR by spot in the rotation, assuming 17 slots for each spot in the rotation. For the fifth spot, I used 17-plus players as some years there were leftovers.

There were two main things that stood out to me about this data that I thought were worth pointing out.

First, we need some perspective as to what the scale is generally considered when it comes to WAR. FanGraphs does a nice job explaining the stat and providing some context:

Scrub: 0-1 WAR

Role player: 1-2 WAR

Solid starter: 2-3 WAR

Good player: 3-4 WAR

All-Star: 4-5 WAR

Superstar: 5-6 WAR


Aces, should you be able to get one, are huge difference makers. A true No. 1 starter is a guy who is capable of winning the Cy Young Awar. These guys stop losing streaks, the guys other teams don’t want to face. However, how difficult is it to get a guy who pitches so well that he compiles a WAR of 6 or higher?

Seeing that I write a Cubs blog, I decided to look back at the Cubs and see what we find. I looked only at the expansion era (1961-2013) and came up with a total of just 15 instances where the Cubs had a pitcher who would qualify as a No. 1. Here is the list:

Fergie Jenkins, 1971: 10.3

Dick Ellsworth, 1963: 10.2

Rick Reuschel, 1977: 9.4

Greg Maddux, 1992: 9.2

Bill Hands, 1969: 8.4

Mark Prior, 2003: 7.4

Fergie Jenkins, 1970: 7.3

Fergie Jenkins, 1969: 7.2

Ryan Dempster, 2008: 7.0

Carlos Zambrano, 2004: 6.7

Ken Holtzman, 1970: 6.4

Kerry Wood, 2003: 6.2

Fergie Jenkins, 1968: 6.2

Rick Sutcliffe, 1987: 6.1

Don Cardwell, 1961: 6.1

It's not as easy as you might think, so when it happens in Chicago, we need to pay attention. That's what made 2003 so special, with Mark Prior and Kerry Wood. However, aside from Fergie Jenkins, the Cubs haven’t had a guy actually repeat this for more than one season.

The fifth starter spot is essentially garbage. Looking at the chart and the legend, we see that the average WAR of 0.2 is a replacement-level pitcher.

That got me wondering if it was even worth it to go with the five-man rotation. Would it be better to find a way to use a four-man rotation in an effort to get more out of the quality guys and simply use them fewer innings? I'm not sure what the answer is there, but maybe a team will try a four-man rotation again. Ultimately, it shows me that if you can have even a replacement-level pitcher in the fifth spot, you're probably ahead of the game. Essentially just minimize the damage in that spot.

The other thing I found interesting is that the quality produced by the fifth spot in the rotation has declined in recent seasons. It could just be small sample size but in the 14-year period, 2012 and 2013 were the only years we saw below replacement-level from the back-end guys.

After collecting all the data and summarizing it into the chart that shows us what we can expect from each slot, I decided to go back to look to see how the Cubs graded out since 2000 on each of these spots in the rotation based only on guys who qualified for the ERA title with their WAR in parenthesis.

2000 (65-97 record) -- Jon Lieber (3.7) and Kevin Tapani (1.2)

2001 (88-74) -- Lieber (3.9), Wood (3.3), Jason Bere (1.7), Tapani (1.0) and Julian Tavarez (-0.1). (Note: Tavarez missed the 162-inning mark by two outs, so I included him anyway.)

2002 (67-95) -- Matt Clement (4.4) and Wood (4.3)

2003 (88-74) -- Prior (7.4), Wood (6.2), Carlos Zambrano (5.5) and Clement (2.8)

2004 (89-73) -- Zambrano (6.7), Clement (3.7) and Greg Maddux (3.2)

2005 (79-83) -- Zambrano (5.6), Prior (3.6) and Maddux (2.8)

2006 (66-96) -- Zambrano (5.2)

2007 (85-77) -- Ted Lilly (4.1), Zambrano (3.4), Rich Hill (3.4) and Jason Marquis (0.8)

2008 (97-64) -- Ryan Dempster (7.0), Zambrano (4.3), Lilly (4.1) and Marquis (2.5)

2009 (83-78) -- Lilly (5.0), Randy Wells (4.2), Dempster (3.5) and Zambrano (3.0)

2010 (75-87) -- Wells (3.2) and Dempster (3.0)

2011 (71-91) -- Matt Garza (2.8) and Dempster (0.8)

2012 (61-10) -- Jeff Samardzija (1.8)

2013 (66-96) -- Travis Wood (4.4), Samardzija (1.0) and Edwin Jackson (-1.3)

Joe Aiello runs The View From the Bleachers, a blog on the Cubs since 2003.