Previously, I have looked at where the Cubs might improve for 2018 in terms of their pitching and plate discipline, and for the last piece of this mini-puzzle, it's time to focus on defense. The Cubs were historically good in 2016, so some retreat this season in their defensive performance was inevitable, but they were still very good with the rawhide.
In general, I should acknowledge that defensive metrics are finicky and very hard to draw firm conclusions from, unless you are working with at least a few years worth of data. When it comes to whole-team performance, it can almost always feel little like false comparison because the roster changes just enough each season, no matter how much the core remains the same.
But we do have some sense for where the Cubs were defensively last season, imperfect as the measures might be, and that can point us to how they can improve going forward.
First, a basic look at where they have been as a team in the last three seasons:
Here it's helpful to remember that DRS is Defensive Runs Saved, and a great player will get about a +10 here, DEF is Defensive Runs Above Average, and an individual player is considered excellent when he gets a +20, and UZR/150 is one of the older defensive metrics, but it is helpful for working with small sample sizes.
So the obvious takeaway is that the Cubs took a very big leap forward in 2016 and then regressed back to numbers much closer to what they had done in 2015 this past year. This can be a little confusing and surprising, given that the Cubs fielded mostly the same team in all three seasons. Players like Anthony Rizzo and Kris Bryant have posted roughly the same DRS numbers in all three of the aforementioned seasons, but big changes can come from small things. For instance, Dexter Fowler alone accounted for a 13 point swing from 2015 to 2016 just by adjusting his defensive positioning in center field.
Expecting the Cubs to consistently perform on defense like they did in 2016 isn't particularly reasonable, but it is not outlandish to think that they could do better than they did last season.
Some of this comes from optimizing the use of players like Rizzo and Bryant, who are known quantities on defense by now, along with Addison Russell, who has been a well above average shortstop for three seasons, posting DRS scores of +10, +19, and +15 in his major league career.
And it also might mean more of Javy Baez at second base. His no-look tags and finger wags at Yasiel Puig notwithstanding, he bloomed into a pretty steady second baseman in 2017, going from being simply average at the position in 2015 and 2016 to a +5 DRS this past year. He's arguably better at second than he is at shortstop, so the Cubs would benefit most from getting as many innings as possible with Rizzo, Baez, Russell, and Bryant across the infield.
The outfield is less certain, save for Jason Heyward in right field. By coming to the Cubs in 2016, he added 18 defensive runs saved as an outfielder, with 14 of those coming in right field. His improvements at the plate from 2016 to 2017 were modest, but there is no questioning that Heyward brings significant value on defense. In center, the loss of Fowler was significant. Ian Happ proved to be the most valuable in terms of DRS, rating at a +3, so the Cubs might have reason to start him over Albert Almora, Jr. And in left, of course, there's the problem of Kyle Schwarber. He had a -9 DRS in 2017, and this was a significant drop from the unit of Bryant, Chris Coghlan, and Matt Szczur that the Cubs used in that position in the previous season. I have shared Joe Maddon's thoughts on Schwarber's work ethic at improving his defense before, and if you haven't read Jesse Rogers' piece from about a week ago, I'd recommend setting aside some time now. Schwarbs is working his tail off to be a better outfielder, and if Joe Maddon is going to be able to pencil him into the lineup consistently, the Cubs need Schwarber's offseason work to pay off.
Behind the plate, Willson Contreras has really been a revelation. In 2015, David Ross was their best defender, but he was backing up Miguel Montero, who lagged behind defensively. The following year, Montero got worse and Ross got better and Contreras debuted, but in 2017, Contreras gave a full taste of what he is capable of. After being a +1 in DRS in 2016, Willson improved to +7 last season.
The key for the Cubs in 2018 probably lies in consistency in their infield, Kyle Schwarber actually improving, and Willson Contreras fully taking the reins behind the plate. This does mean that finding playing time for Happ, Ben Zobrist, or Almora might be more difficult, but if the Cubs are serious about getting better on defense in 2018, they will either need to bet on Schwarber improving with his glove or trade him, and they will also have to decide what they have in Happ and Albert Almora. Both are heavy with potential, but neither have wowed on defense just yet. One of the two needs to start in center field, and right now Happ appears to be the better choice, especially on defense.
The Cubs of 2018, at least defensively, will probably be more like the 2017 and 2015 iterations, and as we have seen, that can work just fine. But if they want to do better than that, this might mean some consistency in the lineup and sacrificing some of the playing time of their complementary pieces.