Jon Lester Was Due For Some Statistical Regression

John Schabaker/ via Flickr.com

The Chicago Cubs $155 million starting pitcher Jon Lester is still really good at baseball.

However, if you tuned into the Chicago Cubs July 9 matchup against the Pittsburgh Pirates and had never seen Lester pitch before you wouldn’t have come to that conclusion.

Lester sputtered through the first inning of that matchup, allowing ten runs (four earned) on six hits including a grand slam. He recorded just two outs as 12 Pirate batters stepped to the plate that inning. It was the first start of his career that he failed to make it through the first inning of a game.

Obviously, that start was a statistical anomaly that observers overblew to a doomsday narrative because of the Cubs bitterly disappointing start to the 2017 season. While it’s unfair to draw conclusions based on one bad outing, it’s not like this start represented a singular stain on a season of brilliance.

In 18 starts prior to that game, Lester accumulated a 3.94 ERA and a 5–5 record. Overall, Lester’s 3.95 cumulative ERA is about half a run higher than his career average and about 1.5 runs higher than the 2.44 ERA he posted last season.

Last year, he made the All-Star game and finished second in National League Cy Young award voting. This season, he ranks 49th in ERA among MLB starting pitchers with at least 80 innings of work under their belts.

After pitching like an ace for most of his career, Lester has looked more like a two or three starter this season. However, Lester’s regression was predictable and has more to do with non-replicable extraneous factors than Lester suddenly being a bad pitcher.

Lester’s 2016 Season Was Amazing and Therefore Extremely Difficult to Reciprocate

In two of the last three seasons, Lester has posted an ERA below 2.50.

Unless your name is Clayton Kershaw or Pedro Martinez, accomplishing this feat more than two times is a heck of a challenge. Below is a summary of qualified starters who’ve posted an ERA below 2.50 for an entire season since 2000 (used FanGraphs.com leaderboards to find this data). Bolded names are players who have accomplished the feat at least twice since 2000.

  • 2016: Jon Lester; Kyle Hendricks
  • 2015: Zach Greinke; Jake Arrieta; Clayton Kershaw; David Price, Dallas Keuchel
  • 2014: Kershaw; Felix Hernandez, Chris Sale; Johnny Cueto; Adam Wainwright; Doug Fister; Corey Kluber, Lester; Hamels
  • 2013: Kershaw; Jose Fernandez; Matt Harvey
  • 2012: Nobody
  • 2011: Kershaw; Roy Halladay; Cliff Lee; Justin Verlander; Jered Weaver
  • 2010: Hernandez; Josh Johnson; Clay Buchholz; Wainwright; Halladay
  • 2009: Greinke; Chris Carpenter; Tim Lincecum; Hernandez
  • 2008: Nobody
  • 2007: Nobody
  • 2006: Nobody
  • 2005: Roger Clemens; Andy Pettitte
  • 2004: Jake Peavy
  • 2003: Pedro Martinez; Jason Schmidt; Kevin Brown; Mark Prior
  • 2002: Martinez; Randy Johnson
  • 2001: Nobody
  • 2000: Martinez

Since 2000, only seven qualified pitchers (including Jon Lester) have posted ERAs below 2.50 in at least two seasons. Pedro Martinez, Felix Hernandez, and Clayton Kershaw are the only pitchers to do it on at least three occasions since 2000.

Therefore, expecting Lester to reciprocate the 2.44 ERA he posted last season is an unfair expectation. Yes, the 3.95 ERA this season is a tad unsightly, but he has still pitched really well in long stretches (his 3.41 ERA across six starts in June is better than his career average).

Statistical fluctuation from season to season is expected especially from a 33-year-old pitcher with over 2,200 innings of career mileage on his arm. Lester hasn’t pitched his best this season, but he certainly hasn’t been bad when you look at his body of work as a whole. Plus, a 162-game season tends to serve as the ultimate equalizer suggesting that the 3.95 ERA is destined to dip down more towards his 3.47 career average by the end of the season.

Amazing Luck Turned Into Just Okay Luck

Used FanGraphs.com for stats in this section.

Lester’s dream season in 2016 coincided with some irrationally good luck.

His 3.41 fielding independent pitching number (FIP) was almost a run worse than his ERA; representing the most dramatic FIP-ERA discrepancy of his career. This suggests that his 2.44 ERA was a bit of an anomaly (when he posted a 2.46 ERA in 2015 his FIP was 2.80).

Last season, he surrendered a .256 batting average on balls in play (league average is .300) despite FanGraphs.com classifying 26.8 percent of that contact as hard contact. To put this in perspective, he has given up 27 percent hard contact this season and has actually given up more soft contact than a season ago, but still has posted a .299 BaBIP this season.

The angel responsible for all this good luck was the Cubs historically good defense last season. In 2016, the Cubs led MLB by a significant margin in ultimate zone rating (UZR). Logically, a good defense turns batted balls into outs thus sinking BaBIP and ERA numbers for pitchers. This season, the Cubs defense has come down to earth in the form of a collective 12.9 UZR which ranks eighth in MLB and is a far cry from the dominant defense the Cubs had last season.

Another unearthly inflated statistic from a season ago has plummeted this season further contributing to his woes.

Last season, Lester posted a 84.9 percent left on base percentage (LOB%) which was so absurdly high that it doesn’t even register on FanGraphs’ chart to measure the value of the statistic. It also represented the highest mark among qualified starters last season.

This LOB % came despite Lester’s inability to hold men on base and despite a 8.7 strikeout per nine inning average which was his worst rate in the past four seasons (generally pitchers with high LOB % are high strikeout pitchers). Again, the Cubs excellent defense helped him in this category.

Lester hasn’t pitched his best this season by any stretch of the imagination; however, inflated BaBIP and deflated LOB % as a result of a worse defense behind him coupled with just plain bad luck have contributed to his regression

Tired Arm

Like most of the Cubs starters, Lester has had trouble generating velocity on his pitches this season (Snipped from BrooksBaseball.net; highlights on second chart denote pitches that Lester has thrown slower on average than last year).


Given his workload during the Cubs World Series championship run last season, it isn’t surprising that he has lost life on his pitches. Lester pitched 202.2 innings during the 2016 regular season and followed that workload up with 35.2 more innings during the postseason. He has pitched 200+ innings in each of the last five seasons and has pitched in the postseason the last four seasons.

He is also 33 years old and has over 2,200 innings of work on his arm between the regular season and postseason. Therefore, it shouldn’t come as a surprise that velocity issues have plagued him this season and stunted his chance of reciprocating the numbers he posted a season ago.

This Is All (Mostly) Normal

Nothing is wrong with Jon Lester, but these are some reasons why he hasn’t enjoyed the same level of success as a season ago. This regression wasn’t too difficult to predict and probably explains why Zips and Streamer projected Lester to finish the 2017 season with a 3.35 and 3.73 ERA respectively.

Nonetheless, despite the statistically disappointing beginning to the season, Lester remains a key cog in a Chicago Cubs starting rotation that needs to do its part to help this team make the playoffs. Lester hasn’t exactly helped them do that with the 0.4 WAR he’s accumulated thus far this season, but he hasn’t performed like a replacement level pitcher either.

It could be worse. Lester hasn’t pitched well this season, yet he still has a decent 3.95 ERA and a winning record. He has also posted a 1.80 ERA through two second half starts, lasting seven innings in one game and eight innings in the other.

The best is yet to come for the Chicago Cubs left-handed ace and expect those numbers to positively regress towards his career norms as the season continues.

Paul Steeno spent 11 years pretending he was good at running. After hanging up the track spikes and officially becoming an elite hobby jogger, he decided to do something that he was actually good at: like writing about the Cubs. He is also a perpetually frustrated Chicago Bulls fan. This one time he got super lucky and ran 3:52 in the 1500 meter run.