The Mariners went 5-2 over the last week to improve to 16-11 on the season, and a big reason why was the performance of the club's bullpen over that span. Seattle relievers posted a 2.38 ERA with 28 strikeouts and eight walks over 22 2/3 innings, earning The Hartford MLB

The Mariners went 5-2 over the last week to improve to 16-11 on the season, and a big reason why was the performance of the club's bullpen over that span. Seattle relievers posted a 2.38 ERA with 28 strikeouts and eight walks over 22 2/3 innings, earning The Hartford MLB Bullpen of the Week for April 23-29.

As part of The Hartford Prevailing Moments program, each Monday throughout the 2018 season, MLB.com is honoring The Hartford MLB Bullpen of the Week. 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 Mariners' relief corps finished the week with a score of 105.5, ahead of the second-place D-backs (98) and third-place Yankees (87.5). Left-hander James Pazos tossed 2 2/3 scoreless frames with four strikeouts during the week, right-hander Juan Nicasio tossed four scoreless innings with six strikeouts and closer Edwin Diaz was also unscored upon in four innings, walking one and striking out eight, while picking up four saves and lowering his season ERA to 0.63.

The unexpected: Seattle starter James Paxton tossed six strong innings against the Indians on Thursday, leaving the game with a 4-2 lead. But following a stretch of 9 2/3 scoreless frames from the bullpen dating back to Monday, Marc Rzepczynski and Dan Altavilla each surrendered run-scoring hits as Cleveland tied the game at 4 in the seventh.

How they prevailed: The Mariners scored in the top of the eighth on a Kyle Seager RBI double, and Nicasio came on for a perfect bottom half of the frame. Diaz then shut the door in the ninth, inducing a fly ball from Jason Kipnis and striking out Jose Ramirez with the tying run on first base (walk) to close out the one-run victory.

Manny Randhawa is a reporter for MLB.com.