The New York Yankees stunned the Cleveland Indians -- and a good portion of the baseball world -- by knocking the club with the best record in the American League out of the postseason.
The Yankees did it in dramatic fashion, too, dropping the first two games of the best-of-five AL Division Series presented by Doosan before rallying to win the next three, including Wednesday's winner-take-all Game 5 on the road at Progressive Field.
One reason why New York completed the comeback was the overall excellence of its relief pitching, and the performances by that group were enough to earn the Yankees the title of "Bullpen of the Week presented by The Hartford" for the Division Series round.
As part of the MLB Prevailing Moments program, MLB.com has honored the "Bullpen of the Week presented by The Hartford" throughout the 2017 season. 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 was compiled for each week during the regular season. 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 five points for a save
• Subtract two points for each hit allowed
• Subtract four points for each earned run allowed
• Subtract two points for each unearned run allowed
• Subtract one point for each walk
• Subtract five points for a blown save
Similar considerations will be used to measure bullpen performance during the postseason.
The Yankees' bullpen allowed six earned runs on 10 hits over 20 innings in the ALDS. Relievers struck out 29 batters, against nine walks, and earned saves in each of their three victories.
Closer Aroldis Chapman was even more of a standout than usual, appearing in three games and pitching 5 2/3 scoreless innings, giving up four hits and striking out 10. Tommy Kahnle was also strong, pitching in two games and striking out five over 2 2/3 scoreless frames.
The unexpected: With everything on the line in Game 5 and starter CC Sabathia dominating the Indians through the first four innings, the Yankees probably felt they could ride the veteran for another two or three frames before turning it over to the 'pen. But Sabathia faltered quickly and gave up two runs in the fifth, as the Indians cut the Yanks' lead to 3-2 and the Cleveland crowd got back into it.
How they prevailed:David Robertson pitched 2 2/3 hitless innings, striking out two and walking one. That paved the way for Chapman to do what he does best -- closing it out with four strikeouts in the final two innings to start the celebration.
"Chappy's a winner, and that's why we went out and got him again, because we knew that he was really, really good at what he did," Yankees manager Joe Girardi said after Game 5. "And he has obviously pitched in the World Series and loves the competition. I mean, his innings were great this whole series.
"And everybody, everyone played a part in this."
Doug Miller is a reporter for MLB.com. Follow him on Twitter @DougMillerMLB. This story was not subject to the approval of Major League Baseball or its clubs.