The Cubs' bullpen was dominant over 25 innings pitched last week, helping Chicago win four of seven games vs. the Braves and Reds by posting a 1.80 ERA. All but three Cubs relievers finished the week unscored upon, helping the relief corps earn the Bullpen of the Week presented by The Hartford for the week of May 14-20.
As part of The Hartford Prevailing Moments program, each Monday throughout the 2018 season, MLB.com is honoring the previous week's top relief corps. An industry-wide panel of MLB experts, including legendary stats guru Bill James, constructed a metric based on James' widely renowned game-score formula, to provide a weekly measurement of team-bullpen performance.
Here's how the Bullpen Rating System is compiled for each week. For reference, a weekly score of 100 is considered outstanding:
• Add 1.5 points for each out recorded

• Add 1.5 points for each strikeout

• Add 5 points for a save

• Subtract 2 points for each hit allowed

• Subtract 4 points for each earned run allowed

• Subtract 2 points for each unearned run allowed

• Subtract 1 point for each walk

• Subtract 5 points for a blown save
The Cubs finished the week with a score of 104.5, edging out the Giants (97), Rays (96.5) and A's (96). Pedro Strop (5 scoreless innings), Mike Montgomery (4), Brandon Morrow (3), Steve Cishek (2 2/3), Brian Duensing (2 1/3) and Randy Rosario (2) all went unscored upon, combining to strike out 23 while walking seven.

The unexpected:Yu Darvish started last Tuesday's game against the Braves in Atlanta, and gave up one run over four innings, but had to exit the game early due to cramping in his right calf. The two clubs were tied at 1.
How they prevailed: Four Cubs relievers combined to hold Atlanta's offense to one run the rest of the way, giving Chicago's hitters the chance to score twice in the top of the ninth in an eventual 3-2 victory. Montgomery allowed a hit and a walk over two scoreless frames in the fifth and sixth, Strop tossed a scoreless seventh, and after C.J. Edwards gave up a run in the eighth, Morrow closed out the game to pick up his 10th save of the year.