Chicago Cubs: A statistical analysis of the National League Central

The Chicago Cubs are aiming for a third National League Central title in as many seasons – but face improved division rivals in the Cardinals and Brewers.

Note: This is Part I of a three-part series evaluating the Chicago Cubs and the rest of the National League Central. 

Most articles build toward a shocking reveal or unexpected twist. This is not one of those articles. infield positions avoid “burying the lede,” let me go on the record in saying, unequivocally, yes, the Chicago Cubs are still very much the team to beat in the NL Central.

As this article will convey, it isn’t even particularly close. While this assertion will elate Cubs fans and irritate those who are not (mainly Brewers and Cardinals fans), the numbers don’t (usually) lie.

It stands to reason the team that played in three consecutive NL Championship Series is considered the favorite in their division. By no means should there be a significant amount of pushback here. But there has been a lot of chatter around this storyline nonetheless. Discussions cite bold offseason moves, overrated players and circumstantial evidence that implies a tightening of a gap. Remember, Chicago ran away with the division in 2016 but struggled to sew up the Central until late last season.

To clarify the landscape within the National League Central Division, this article will speak to specific measures of success and will qualify each team within the context of those measures.

A consistent way to evaluate the teams

Before we can properly assess the teams in the National League Central, we must first set the ground rules. Hopefully, this leads to an objective assessment. In this particular analysis, we will look at each of six functional positional groupings. These include catcher, infield, outfield, starting pitcher, relief pitcher and closer.

Using a series of standard and sabermetric statistics, we can rank each NL Central team on a 1-to-5 scale. (Note: 5 being the best, 1 being the worst).

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Identifying the “right” analytical factors is where the magic really happens. Sure, it’s great to have a catcher with speed or a starting pitcher with a great eye at the plate, but neither trait better prepares the player to be a solid contributor at his position of choice.

There is no ‘I’ in team

Rather than focusing on overall, individual attributes – which are mired in subjective opinion and “beauty-in-the-eye-of-the-beholder” bias – this exercise takes a more objective approach. We first identify what defines “good” as it relates to a unique position group and then assess each team’s ability to satisfy that definition.

The result is a set of data that objectively frames a relative valuation of the six position groups. These results do not necessarily project that a given team excels at a given position. It is impossible to make such a determination from an analysis that did not include teams outside of the division. But it does clearly frame if Team A is better than Team B at Skill 1 and, in some cases, also frame how much better Team A may be at Skill 1.

Let’s get down and dirty – metrics style

Be forewarned. There are lots and lots of numbers that will follow here. Numbers are boring. They are sterile. Numbers can be manipulated. But numbers are also necessary when taking personal opinion and the dreaded “eye test” out of the equation, which is what I’ve tried to do here. Rather than run from those numbers, I will offer a bit of an informational olive branch by trying to define the numerical values up front better. To that end:

Notes:

• Cumulative stats – such as WAR – are expressed as per game averages, unless otherwise noted. This is important to remember for context throughout the article.
• Per game averages reflect data covering a four-year sample size from 2014 to 2017 (where applicable; obviously younger players with limited service years allow only for review of however many years they’ve had Major League roster time). Using an expanded time scale helps mitigate some of the risks that comes with only assessing the immediate past. Baseball is a sport of trends and consistency where, as the saying goes, water tends to find its level. As such, utilizing a broader sampling of data helps account for the trending.
• Because cumulative stats are broken down to their lowest level (per game average), the rankings herein use a “Play Percentage” estimate for each individual likely to take up a roster spot in 2018. That value was used to determine the approximate number of games played for each of those individuals. Through these means, a fairly representative baseline was created which allowed a very linear evolution from per game average to predicted 2018 season-long results.
• Key sabermetric statistics such as WAR (Wins Above Replacement), UZR (Ultimate Zone Rating), ISO (“ISOlated power” – measure of extra base hitting tendencies), BsR (Base Running measure of additional runs created), FIP (Fielding Independent Pitching), wOBA (weighted On Base Average) and BABIP (Batting Average on Balls In Play) are leaned on heavily throughout these rankings.

Let’s begin, shall we?

Sabermetric statistics were developed to look “beyond the box score” and to allow value to be quantified in a different, cleaner, more comprehensive way. It marries a variety of disparate data elements together to create a more singular, concise way to measure player value. To learn more about these statistical measures, visit Fangraphs, which was used as a source for this article.

We’ll start the evaluations with the catching and infield positions. Subsequent articles will follow in each of the next two days to round out the outfield, as well as pitching staffs.

Cubs dominate, lead division in catching value

Figure 1. Catcher Comparison

Unsurprisingly, the Cubs, who are led by a power-hitting catcher with great defensive skills and tremendous overall upside, rate highest on this list with the other four more closely matched with one another. Since this is a relative comparison, the conclusion should be that the Cubs grade out as a unit that is superior in all measured categories relative to the rest of the division.

Milwaukee, St. Louis have a ways to go

Beyond that initial insight, it is also apparent that the Brewers provide more offense than most of the rest of the division (aside from the Cubs) from their catcher spot. The Reds, meanwhile, have a superior defensive capability (again, when omitting the Cubs). It should also be noted that Pittsburgh, while considerably lacking in power potential, sports the second-highest wOBA of the group, which is to say they do get on base at a relatively high clip.

One additional noteworthy conclusion here. Even though Yadier Molina grades out as a top performer among NL Central catchers, the likelihood that he’ll play less than 130 games is a big factor. Add in the quality and production of the other St. Louis catchers and the Cardinals’ overall positional ranking suffers.

Again, it is critical to remember these lists do not predict the best individual players, but rather highlight the relative strength of each unit as compared to the others.

Next: Remembering Theo's best trades

That’s it for our first installment. Both Friday and Saturday at noon C.T., we’ll have the subsequent pieces. Friday will focus on infielders and outfielders, while Saturday delves into the pitching comparisons in the division.