The Chicago Cubs defeated the Pittsburgh Pirates on Wednesday night at PNC Park in the National League wild-card game. The win marks the Cubs' first postseason victory since 2003 (Chicago was swept in both the 2007 and 2008 NLDS). It also sets up an NL Central showdown between two teams that are longtime rivals in part due to geographic overlap of their respective fan bases.
The Cubs won 97 games this season, which was somehow only good enough to finish in third place in the Central. (Remember that last year the Cards won the division with 90 victories on their ledger.) The Cardinals won 100 games. Only three games separate the two clubs, so it's no surprise that their cumulative statistics are relatively close as well.
But first a caveat.
Evaluating both of these teams by their season-as-a-whole stats—which this post does—has its shortcomings. Such an exercise always does due to trades, promotions, and player health. These issues are even more prevalent with this year's Chicago and St. Louis teams. The Cardinals have been hit hard by injuries and it's difficult to say how healthy some of their best batters are heading into the NLDS. Moreover, they lost Carlos Martinez, their best starter in 2015, to a shoulder strain which means he will miss the entire postseason. The Cubs have promoted their crop of top prospects in a staggered fashion over the course of the season. The teams' NLDS rosters are going to be a bit different from the ones they opened the season with at Wrigley Field in April.
With these shortcomings in mind, let's have a look at the two teams' 2015 stats compare in the areas of starting pitching, relief pitching, and batting. The Cardinals' team stats are in red boxes with white text. The Cubs' are in blue boxes. The stats come from Fangraphs.
For relievers, ERA is a very volatile statistic. Relievers don't tend to accumulate many innings. The team innings-pitched totals shown above illustrate this. The Chicago and St. Louis bullpens totaled far fewer innings than any three primary rotation members combined. Of course, over 485+ innings, ERA is perhaps a bit more reliable than for an individual reliever. Nonetheless, a club's cumulative bullpen ERA is the combination of a bunch of tiny and extremely volatile component parts.
How much stock does one put in ERA as a measure of pitcher performance? I tend to lean more toward FIP. It is at once more focused and casts a wider net. The stat burrows in on the stats that we know that a pitcher has the most individual control over: strikeouts, walks, hit batsmen, and homers than he does runs scored. Thus, it's more encompassing of a pitcher's performance than earned runs allowed. That feature (and perhaps bug) also makes it more focused: Unlike ERA, fielding and the official scorer doesn't come into play. By this measure, the Cubs have a slight leg up on the Cards. Thanks to stranding opposing baserunners, the Cardinals have a healthy ERA lead.
Then there's the wild card: Adam Wainwright. The St. Louis ace is likely to join the bullpen (we're likely to find out on Thursday for sure). And I think that gives the Cardinals a slight edge when it comes to relief pitching—even if their bullpen may very well have fewer arms in it than we're accustomed to seeing.
When it comes to team starting pitcher stats, we can add an additional flaw to the issues with team stats cited above. Not every member of the clubs' five-man rotations will make a start in the NLDS. This can favor a top-heavy rotation (like the Cubs') as opposed to a more balanced five-man (like the Cards') more than during the course of the 162-game regular season. Manager Mike Matheny deciding not to pitch his best pitcher in Game 1 sets the club up to potentially give the ball to John Lackey (2.77 ERA, 3.57 FIP) against Jon Lester (3.34 ERA, 2.92 FIP). What you think about this decision is likely related to whether you think the Cubs or Cardinals have the better starting pitching this series.
To me, Lester is clearly a better pitcher than Lackey. This is as true for 2015 as it is for their careers. In 2015, Lester's peripherals (while pitching his home games in a hitter-friendly park) are superior to Lackey's (while pitching his home games in a pitcher-friendly park). It would be one thing if the veteran Lackey had a track record of posting an ERA lower than his FIP, but he doesn't. Lackey's career ERA is 3.92 to a 3.86 FIP. So it's unreasonable to expect his run suppression to so healthily outpace his peripherals. It's the postseason, though, and just about anything is possible. Hopefully Lackey and Lester's ERAs continue to defy peripherals gravity. Sitting here today, though, it appears that Matheny's faith in veteran proveyness has already hurt the Cards' chances of winning the series, even if only slightly.
Overall, though, I'll take the Cubs' peripherals over the Cardinals' strand-rate-reliant ERA.
The Cubs plated 689 runs in 2015; the Cards, 647. That 42-run differential makes a difference in runs scored per game of 0.26: 4.25 to 3.99. Clearly the Cubs have the better hitting attack. Not so fast.
As noted above, the Cubs played their home games in the more hitter-friendly confines of Wrigley. The Cardinals call the pitcher haven that is Busch Stadium home. Thus, it's interesting that the Cards posted a higher collective BA and equal OBP to the Cubs, even if they hit for less power. Overall, using the linear-weighted wOBA, the Cubs' attack was just two points higher on a rate basis. Factor in home park effects, and the Cardinals hit at a rate on par with the Cubs. Further, as with the clubs' ERA discrepancy, timing was a difference-maker as well.
Despite their overall rates of batting production being roughly equal when timing is ignored and home parks are taken into effect, I'm going to cheat a little. I'm going to expand this category from batting to offense and include baserunning. The Cubs run the bases extremely well; the Cards aren't all that great overall. Chicago has been worth 15.8 baserunning runs, according to Fangraphs, which ranks second in all of baseball behind the Rangers. The Cardinals have posted 0.6 baserunning runs, a roughly average number which unsurprisingly ranks 15th in the game.
Then there's health. I'm not sold on Matt Holliday, Randal Grichuk, or Yadier Molina's health, but I think they will get the lion's share of plate appearances in left, center, and at catcher. And I think that will hurt the Cardinals a bit.
The Cubs have the advantage going into the NLDS. Like all advantages in October, Chicago's is slight. And that means anything can happen. This series is going to be a lot of fun.