Don’t take Baseball Prospectus’ Cubs projection too seriously

For Cubs fans newly used to winning baseball, it came as a system shock this winter when Baseball Prospectus’ PECOTA projections listed the North Siders at 79-83, last in the National League Central.

That since has moved up to 80-82. But after 95 victories last season and no fewer than 92 in the last four, how could anyone project a record below .500?

It shouldn’t be taken too seriously. There are solid reasons to project decline, based on precedent by other players. The past is a guide to the future, but it’s not a perfect roadmap.

As projection systems are refined, even small differences can have a large effect. A click on projected standings at Fangraphs.com shows the Cubs at 86-76, first in the division.

The poster child for PECOTA’s Cubs projection seems to be left-hander Jon Lester, who was 18-6 with a 3.32 ERA in 2018, his age-34 season. There were signs of trouble in Lester’s 4.39 FIP and a strikeout rate that declined to 7.38 per nine innings from 8.96 in 2017.

Lester’s percentage of runners left on base was 80.3 last season, compared with his career average of 70.7. Figures that far outside the norm usually don’t hold up from year to year.

Those are among the factors in his projected 10-11 record with a 4.43 ERA in 2019.

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It’s not that PECOTA is seeing Lester’s record as luck rather than skill at pitching to situations. Regardless of reason, projections are based on what has happened to other pitchers in comparable situations.

In 2000-17, there were nine starting pitchers with at least 15 victories, an ERA of 3.50 or lower, a FIP of 4.00 or higher and a half-strikeout or more per nine innings fewer than the previous season. Six had ERAs of 4.50 or higher the next season.

Four follow-up seasons were affected by injury, as Matt Harrison, Daisuke Matsuzaka, Hideo Nomo and Joe Mays went from a combined 69-40 to a combined 12-27. The others won in double figures again but went from 85-38 to 74-50.

There are good seasons on the list, including Jamie Moyer following 20-6, 3.43 with 13-8, 3.32 and Nomo, in one of his two appearances on the list, following 16-6, 3.39 with 16-13, 3.09 before collapsing to 4-11, 8.25.

PECOTA and other projection systems weigh more factors over longer periods of time. Overall, however, pitchers with records similar to Lester’s have declined.

Beyond Lester, history suggests something less than a full recovery from his shoulder injury for third baseman Kris Bryant. PECOTA projects his WARP — the Baseball Prospectus version of WAR — at 3.9, higher than his 1.9 last season but not as high as his 6.1 and 5.3 in 2016-17.

Is Javy Baez’s 2018 season a breakthrough or an outlier? Past results suggest something in between, so his projected 3.0 WARP is lower than his 4.6 of 2018 but higher than a pair of 1.3s in 2016-17.

Individual ups and downs lead to a projection of a Cubs drop, but that’s not destiny. History might be a guide, but it doesn’t always repeat.