Of the many factors that fueled the Cubs’ historic run to a World Series title, it’s hard to underestimate the impact of the three-headed monster of Kyle Hendricks, Jon Lester and Jake Arrieta. Not only did each of their top three starters excel when it mattered most, but they had been propelling the Cubs’ success all season.
That is evident, given that Hendricks and Lester make up two-thirds of the National League Cy Young award finalists, and that Arrieta’s season was disappointing only in contrast to his own 2015 Cy Young campaign.
Though less glamorous, the back-end of the rotation played an important role as well. John Lackey and Jason Hammel’s respective ERAs of 3.35 and 3.83 were plenty good for a fourth and fifth starter. Collectively, all of the Cubs’ starters compiled a 2.96 ERA. That mark didn’t just lead the majors; it practically lapped the competition, as no other team’s rotation finished with an ERA below 3.60.
This was a talented quintet heading into this season, but it would have been hard to foresee this level of success. In 2015, only Arrieta and Lackey had ERAs below 3.30.
So what happened? Did Arrieta’s rising tide in 2015 lift the entire rotation in 2016? Did the Cubs unlock some critical pitching secret? Or was their minuscule rotation ERA a mirage?
When it came to run prevention (or at least run prevention as measured by ERA), the Cubs were clearly in class by themselves. Yet in terms of the aspects of run prevention their starters could control — avoiding contact, walks and fly balls — they were hardly alone. They weren’t even the best, if we are to use xFIP as a measure of those skills. The 3.76 xFIP put up by the Cubs’ starters ranked third, behind the Dodgers (3.69) and Mets (3.72), and was only slightly lower than that of the Nationals (3.81) and Indians (3.85). If the Cubs’ starters weren’t substantially better at those three skills than pitchers from a handful of other rotations, are we at risk of overrating them for next season?
It wasn’t just one or two pitchers whose ERA may have been skewed. Each of the Cubs’ five primary starting pitchers had an ERA that was lower than his xFIP. Both Hendricks and Lester finished with ERAs that were more than a run lower than their xFIPs. Their skill indicators were indicative of pitchers with mid-3.00s ERAs, but because both had extremely favorable BABIP and strand rates, they were able to post sub-2.50 ERAs.
Lester and Hendricks were among just six qualifying starters with a strand rate above 81 percent. Lester’s 84.9 percent strand rate was not only the lowest for any qualifier this season, it was the second-lowest since J.A. Happ compiled an 85.2 percent rate in 2009 (the highest rate was Zack Greinke’s 86.5 percent mark in 2015).
While Hendricks and Lester were the biggest overachievers according to xFIP, the whole rotation benefited from ultra-low BABIPs and strand rates that were at least two percentage points below the major league average of 72.9 percent. Given that the entire Cubs rotation posted favorable rates, one has to wonder if they have found a way to render xFIP irrelevant.
Before we jump to that conclusion, let’s remember that xFIP stands for Expected Fielding Independent Pitching. If we take a literal interpretation of xFIP, we can conclude that, without the defense supporting them, the Cubs had a good rotation, and maybe even a great one, but they weren’t necessarily elite.
What is clear is that the Cubs did boast an elite defense this season. According to FanGraphs, they compiled 69.0 defensive runs above average (DEF), which was more than 15 runs worth of defensive value greater than that accrued by any other team. As the graph below shows (with the Cubs alone in the upper-left corner), teams that were above-average defensively stood a better chance of having a rotation that outperformed their xFIP.
It stands to reason that pitchers who benefit from superior team defense will fare better at preventing hits on balls in play and stranding baserunners. The Cubs ranked ninth in DEF in 2015, and only two of their seven starters with at least seven starts (Arrieta and Dan Haren) outperformed their xFIPs. This season, there were upgrades in the middle infield, as Addison Russell improved his play at shortstop, and Javier Baez improved upon Russell’s 2015 production at second base. In right field, Jason Heyward was a dramatic improvement over Jorge Soler. Just on the basis of those changes alone, the defense could have had an across-the-board impact on the Cubs’ rotation.
Yet if we break down each pitcher’s BABIP on airborne balls or batting average allowed on grounders, no clear pattern emerges. Arrieta, Hendricks and Hammel each did an above-average job of getting outs on grounders, but Lester and Lackey were normal in this regard. Lester, Arrieta and Lackey may have received significant help from Heyward and the rest of the Cubs’ outfield, but that did not extend to Hammel or Hendricks. Lackey owed much of his low BABIP to getting line drive outs, but that seems like a random result, given how much higher the rest of the rotation’s line drive BABIPs were.
The Cubs’ defense was so far ahead of the rest of the majors, it’s hard not to give them some credit for the rotation’s success. At least for the four starters who appear to be returning for 2017, there is no reason to draft them next season as if they will fully regress to the level of their xFIP. If you do, not only will you miss out on them on draft day, but you will be undervaluing them for the coming year.
As for Hammel, who is now a free agent, he may be able to post a below-average BABIP without the Cubs. He has had a lower-than-average BABIP for three seasons running, including during the latter portion of 2014, which he spent with the Athletics.
Each of the Cubs’ Big Four will be worth drafting in standard mixed leagues next spring, and Arrieta, Lester and Hendricks are all candidates to be among the top-15 starting pitchers in average draft position. Of the four, Hendricks is one least likely to get drafted too early. He may have found a way to legitimately cheat BABIP — and xFIP — as his increased changeup usage and movement led batters to post a lower BABIP against him this season.
The steep decline in Arrieta’s control was partially masked by the .118 batting average he allowed on grounders. No matter how good the Cubs’ infield defense is, that was less than half of the major league average and smells like a fluke. Lester’s .053 fly ball BABIP also looks suspicious, not only because it was so much lower than the major league norm, but also because he allowed a good portion of fly balls in play to left field (see below), which was the relative weak link defensively for the Cubs in the outfield.
Lackey has outperformed his xFIP by at least a run in each of the last two seasons, but it doesn’t look like he’s found any sort of special sauce. This season, his low ERA was BABIP-driven. Last season with the Cardinals, Lackey had a normal .295 BABIP, but he had an 82.6 percent strand rate that was a strong outlier among his recent rates.
Even though Hendricks is the least proven in the group, he is the one I will draft with the greatest confidence. Arrieta and Lester will probably be among the first 10 starters drafted in many leagues, but each could regress just enough to make that a slight overpay.
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