It was already hard enough before this week for opposing hitters to stage a rally against the back end of the Yankees' bullpen. Dellin Betances and Andrew Miller had combined to allow just four earned runs in their first 25 2/3 innings pitched, striking out 49 percent (47-of-96) of the batters they faced.
Last Monday morning, New York was already 10-0 when leading after seven innings. But that day marked the introduction of new Yankees closer Aroldis Chapman, making his season debut after serving a 30-game suspension for MLB's Joint Domestic Violence, Sexual Assault and Child Abuse policy. Chapman, who threw the 77 fastest pitches in the Majors a year ago, brought excitement to every corner of Yankee Stadium this week -- including his own dugout.
:: Bullpen of the Week winners ::
"Everybody is so anxious to see him," said fellow Yankees reliever Kirby Yates. "It's really cool. You can feel the excitement."
With Chapman joining the staff, New York's back end became even more dominant, elevating its status to "Bullpen of the Week presented by The Hartford."
As part of the MLB Prevailing Moments program, each Monday throughout the 2016 season, MLB.com is honoring the "Bullpen of the Week presented by The Hartford." 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 Yankees' bullpen scored 110.5 points this week, while striking out 29 batters and allowing just 17 hits and five earned runs in 28 1/3 innings. On Saturday, Betances, Miller and Chapman pitched in the same game for the first time and were as good as advertised. Over a combined 3 1/3 innings, New York's new three-headed monster allowed no runs, one hit and struck out eight of the 11 batters they faced.

"The way it's going, you try to go six and let those three guys finish it," said Yankees starter Ivan Nova, who picked up the 2-1 win in that game.
Any successful bullpen must be able to overcome some unexpected circumstances, and even the vaunted Yankees' relievers had to overcome adversity this week. Here is a look at their biggest obstacle:
The unexpected: On Tuesday, Yankees ace Masahiro Tanaka endured a rare poor start, allowing six runs over seven innings to the Royals. New York's offense provided seven runs of support, however, and appeared to be where they wanted to be with a 7-6 lead and Miller entering to pitch the eighth. That was until Lorenzo Cain hit a 2-1 pitch over the wall, tying the game at 7 for Kansas City and scoring the first run allowed by Miller all season.
How they prevailed: After Miller faltered, Chapman was there to pick up his teammate. The Yankees' offense rallied back for three runs in the bottom of the eighth, and Chapman shut the door on the Royals. With a runner on third, Chapman threw a 101-mph fastball to Cain and induced a pop fly to seal the 10-7 win for New York.
While the Yankees featured the Bullpen of the Week, they weren't the only club who enjoyed an impressive stretch from their relievers.
The Padres finished with a 106.5 BRS score, just four points shy of New York. Though they did blow one save, San Diego's relievers also struck out 33 batters -- second only to Kansas City's bullpen over the past week. Starter Luis Perdomo lasted just two innings Saturday night, but seven Padres relievers combined to pitch the final 10 frames and help San Diego to an 8-7, 12-inning victory over the Brewers.