Any discussion of the Cubs getting better must always begin with the caveat that they are already very good. This is a supremely talented baseball team, and one that collectively has played in more postseason games in the last three years than anyone else; in fact, they are the only team in baseball to make it at least to the championship series for the past three seasons.
Yesterday I speculated that the front office was approaching the offseason conservatively so far because they are mapping out moves that will come six months or a year from now, so assuming the roster changes little between now and the start of spring training, it is worth examining where the Cubs have some room for improvement.
Like an individual player, progress and growth are never linear, but the Cubs took some steps back in 2017 that need to be reversed in order for them to have a better season in 2018. They commanded the zone less effectively as a pitching staff, they showed lesser plate discipline as an offense, and they slipped rather significantly on defense. Again, we are still talking about a very good baseball team, one that still won 92 games and locked up the division rather handily, so this will admittedly be a delve into some minutiae.
For today, let's focus on the decline in pitching performance.
In 2016, the Cubs were the third-best team in baseball, behind the Dodgers and Nationals, in K%. This year, they slipped down to tenth in K%. This doesn't represent a dramatic change in their own numbers -- it's a 23.6 percent after 24.3 in 2016 -- but the difference is that other teams in the league got so much better. From 2016 to 2017, the highest K% has jumped by over two percent, and along with that, a cluster of teams have made significant jumps in this category, which pushed the Cubs down in the rankings. This is a relatively small thing, yes, but it makes a difference in the day-to-day in terms of a handful of wins or losses. They also suffered a worse walk rate, going up by nearly a percentage point from what it was in 2016. This might not seem like much, but it's a difference of about 60 more total walks in 12 fewer innings.
So where does the improvement in 2018 come from? On the starting staff, a lot of this rests on Kyle Hendricks.
A workhorse in 2016, Hendricks pitched 188 innings across 30 starts, and he had the highest fWAR on the staff, at 4.5. This year, when an injury to his pitching hand cut him to 139 innings and 24 starts, the difference was two wins off of his fWAR, still good enough for second-best on the staff, but they declined across the board, largely because they gave up more homeruns, walked more batters, and the defense allowed much higher BABIPs for the entire rotation.
By himself, a healthy Kyle Hendricks holds a great deal of influence over how the rotation performs as a whole. We should no longer need to be convinced of how good he is. Even in a season when he lost two full ticks on his fastball thanks to a sluggish start, Hendricks still turned in a strong season. If he is healthy, he can by himself impact the rotation for the good.
Letting Jake Arrieta go is the right decision given what it sounds like his asking price is, but the Cubs have not added an arm in Tyler Chatwood or Drew Smyly that is remotely capable of taking his place. Even as his skills have declined, Arrieta is a significantly better than Chatwood has been, road splits taken into consideration and all. There's the dazzling potential in the new guy, but Arrieta has been a superior pitcher.
In the bullpen, the Cubs benefited mightily in 2016 from Aroldis Chapman's second-half presence -- for as good as Wade Davis was last season, he and Chapman are simply at different levels -- but they suffered greatly in 2017 for Justin Wilson's presence. Whatever role he fills in the next season, Wilson might hold the key to a more stable bullpen.
After coming over from Detroit, he walked batters at a near-21 percent clip, and when he did find the zone, opposing hitters put he ball in play for a hit almost 40 percent of the time. His stuff is electric, but Wilson just could not control it after the trade last year. The Cubs badly need him to return to his pre-trade form, before his walk rate doubled, and his strikeout rate lost almost eight points.
Quite simply, the key to the Cubs bullpen in 2018 might just be Justin Wilson returning to form. If he can pitch like he did while he was still wearing a Tigers uniform, the bullpen concerns we have right now might seem silly in hindsight. So much of what plagued him in Chicago still seems inexplicable, but if he can get it right in 2018, that's the difference between a good bullpen and a great one.
Both in the rotation and in the bullpen, the Cubs have pitchers who underperformed -- though for different reasons -- and Kyle Hendricks and Justin Wilson regaining some of their old form will make a monumental difference in 2018.