In a season in which the offense has been mainly responsible for bringing the Cubs from the brink of oblivion to playoff contention, the bullpen has made just as big a turnaround.
Through June 11, the Cubs were 28-37 and 61⁄2 games behind the National League Central-leading Pirates. Their offense was averaging 4.2 runs per game, and their bullpen had a 4.73 ERA that was the sixth-worst in the majors.
Since then, the Cubs entered play Monday having gone 36-22 in their last 58 games. They had scored 5.9 runs per game, and their bullpen had been the fourth-best in the majors with a 3.15 ERA.
The offensive leap has been well-documented, sparked by the return from injury of Cody Bellinger and production up and down the lineup.
In the bullpen, the most obvious change has been elevating Adbert Alzolay into the closer’s role, but he has been a strong contributor all along. In the Cubs’ first 65 games, Alzolay had a 2.10 ERA in 30 innings with three saves and nine strikeouts per nine innings. Since then, he has pitched 252⁄3 innings with a 3.51 ERA, 15 saves and 10.17 strikeouts per nine innings.
By wins above replacement at Fangraphs.com, Alzolay ranks 12th in the majors among relievers at 1.4 — 0.8 in the first 65 games, 0.6 in the last 58.
Mark Leiter Jr. and Julian Merryweather have been among the Cubs’ better relievers early and late.
Leiter, who had a 3.16 ERA in the first 65 games and a 2.80 ERA in the last 58, has pitched well in important situations. By win probability added (WPA), which adds or subtracts how much the result of each plate appearance increases or decreases the chance of winning, Leiter’s 1.16 trails only Alzolay’s 2.32 among Cubs relievers.
WPA reflects expected victories and defeats, so Leiter’s results normally would lead to about 1.16 more victories than with an average pitcher.
Leiter’s WPA includes 0.73 in the last 58 games, even better than Alzolay’s 0.56. But he’s not the club leader during that span. That’s Merryweather, who is at 0.74. Merryweather leads Cubs relievers with 28 innings in the last 58 games, and he has posted a 3.54 ERA with 12.21 strikeouts per nine innings. That comes after a 3.62 ERA and 12.18 strikeouts per nine innings through June 11. He has been consistent.
Michael Fulmer and Javier Assad have made big leaps forward. In the early segment, Fulmer’s ERA was a whopping 5.93 and Assad’s 5.56. Since the turnaround, Fulmer has joined the ranks of the reliable with a 2.10 ERA in 25 innings.
With 24⅓ innings in 10 relief outings in the latter segment, Assad has increased his strikeouts from 5.16 per nine innings to 8.88, decreased his walks per nine innings from 4.37 to 3.70 and put up a microscopic 0.74 ERA. His relief success has led to spot starts.
There has been subtraction from the early pen, too. Brandon Hughes (7.24 ERA early) and Brad Boxberger (5.52) have not been in on the turnaround.
But, as with the offense, the bullpen swing has been deep. Alzolay, Leiter, Merryweather, Fulmer and Assad all have been strong contributors, helping the pen go from a big weakness to one of the reasons the Cubs have been winning.
