Rotation rankings are one thing, but the most important part of data is interval in nature. In other words, what is the distance between the best and the worst. That often tells a more important story than the order in which we put teams. The National League Central is as good an example of this as any division in baseball. The difference between the Cubs and the other teams in the division tell a definite story.

We are ranking rotations based on their pre-season projection according to rosterresource.com. We are using three Baseball Prospectus statistics and their three year averages to rank them. The first is their version of wins above replacement (WARP) to give us the quality and quantity of their work. The other two statistics are more qualitative numbers. The first is their ERA estimator they call “deserved run average.” It essentially calculates what their ERA should be if everything else was equal in the batted ball statistics. The last calculates what opposing hitters actually did against the pitcher as measured by their total average statistic (TAVA). It is calculated to look like batting average, but it includes everything opposing hitters do.

Chicago Cubs

WARP: 17.3 (1st)

DRA: 3.44 (3rd)

TAVA: .234 (1st)

Key Changes

Officially, the Cubs made only one change. They let Jason Hammel (who has yet to sign) leave via free agency and brought in Brett Anderson from the Dodgers. This is classic risk/reward move. His DRA and TAVA are superior to Hammel, but he hasn’t been able to stay healthy. Mike Montgomery is waiting in the wings if he isn’t able to remain healthy. The bigger decision revolves around Jake Arrieta. He will be a free agent after the season.

Unfinished Business

Will Epstein and Hoyer sink another nine figures into a pitcher or will they allow Arrieta to walk? A normal team would consider dealing him, but the Cubs are odds on favorites to win the World Series again. So, he is staying put at least through this season.

Prognosis

The Cubs may have the best setup in all four areas of the game (fourth being the bench), so it is hard to go against them when it comes to the World Series.

Cincinnati Reds

WARP: 1.8 (14th)

DRA: 4.94 (14th)

TAVA: .277 (13th)

Key Changes

They traded Dan Straily to the Marlins. The fact that this constitutes a major defection tells you everything you need to know about this group. Scott Feldman takes his place as he becomes the key veteran just like in 2014 when he signed with the Astros. He’s been here before and I suppose that’s worth something by itself. Otherwise, Homer Bailey returns from the disabled list to anchor the rotation. Let that sink in for a moment.

Unfinished Business

The hope is that young pitchers like Anthony DeScalfini and Brandon Finnegan will take the next step and establish themselves as top of the rotation arms. Both have the talent and pedigree to do it, but that’s been said before about a number of other guys. More than anything, they just need an infusion of talent.

Prognosis

Tanking only works when you get to tank by yourself. When you look around the NL, there are a handful of teams that are operating under the same strategy. Only one can be the worst and get the top pick. So, brace yourself for some bad baseball.

Milwaukee Brewers

WARP: 3.8 (13th)

DRA: 4.56 (11th)

TAVA: .267 (11th)

Key Changes

There were no additions or subtractions from this unit. Welcome to the world of rebuilding. Unfortunately for the Brewers, they aren’t quite as far along as the Reds. They still have a veteran or two they need to shed before they can completely embrace rock bottom. It’s not through lack of trying. Do you want your team to take on Matt Garza? I didn’t think so.

Unfinished Business

Zach Davies is a good start to a rotation and others like Junior Guerra had good seasons last year. Chase Anderson is a decent bottom of the rotation starter. That leaves just two more spots where good young starters could take hold.

Prognosis

David Stearns learned from watching Jeff Luhnow gut the Astros. He even took advantage of his former boss when he dumped Carlos Gomez and Mike Fiers for prized prospects. He knows how to get this done. The question is whether ownership has the stones to embrace a full on rebuilding effort.

Pittsburgh Pirates

WARP: 5.6 (10th)

DRA: 4.67 (12th)

TAVA: .281 (14th)

Key Changes

Truth be told, the numbers above reflect a lack of experience much more than a lack of ability. We really don’t know where the Pirates will go as a rotation. Three of the starters (Jameson Taillon, Chad Kuhl, and Steven Brault) have less than a year of experience. Taillon is highly regarded and fared best in his partial season. Ivan Nova re-signed and the excitement around that deal reveals a great deal. On the one hand, it is sad to see that much hoopla over a pitcher of his track record. On the other hand, it demonstrates their love for reclamation projects.

Unfinished Business

They have been involved on the periphery of the Jose Quintana talks and you can’t think of a better destination for Quintana. He is durable and this is a team that could capitalize more than any other on a top of the rotation arm. Otherwise, they are just keeping their fingers crossed.

Prognosis

There is a path to the playoffs for the Pirates, but it involves little margin for error. Gerrit Cole has to remain healthy and Nova has to continue to pitch like he did following the trade. Then, those other three pitchers have to step up. No problem.

St. Louis Cardinals

WARP: 11.5 (6th)

DRA: 3.95 (7th)

TAVA: .252 (5th)

Key Changes

The return of Lance Lynn allowed the Cardinals to deal from excess. They dealt Jaime Garcia to the Marlins in exchange for John Gant and a minor leaguer. What they don’t have in dominance they make up with depth. This is why they are the odds on favorite to take one of the two wild card slots. Michael Wacha has not lived up to his abbreviated rookie season and if he ever does this could be a very dangerous group.

Unfinished Business

It looks like they will be going to war with this group. The Cardinals are one of those teams that always seems to add good quality depth during the season. It would’t be a huge shock to watch them add a starter if they feel one of their current group hasn’t lived up to their end of the bargain.

Prognosis

The Cardinals will win 90+ games again and will end up being in second place in the NL Central. We like our drama in sports, but sometimes the conclusion is there in front of you.