The Kansas City Royals trio of relievers has received a lot of attention this postseason. Kelvin Herrera, Wade Davis, and Greg Holland all throw some serious cheddar. Also, they have been dominant. All three posted ERAs below 1.50 during the regular season, and in the playoffs they've allowed just three runs in 25.2 innings. Herrera owned baseball's second fastest average fastball at 98.1 miles per hour, and Holland and Davis both fell in the top 15, averaging just under 96 miles per hour.
However, the Royals did not have baseball's hardest throwing bullpen. That distinction belonged to the Atlanta Braves, whose relievers had an average fastball velocity of 93.9 miles per hour. The Royals checked in at 93.5 miles per hour, in a virtual tie for second with the Cincinnati Reds (think Aroldis Chapman) and the Seattle Mariners.
Craig Kimbrel, the Braves closer, averaged 97.1 miles per hour with his heater. Only Chapman and Herrera had a faster fastball. The 26 year-old hurler has dialed up his fastball velocity almost two full miles per hour since he debuted in 2010. His 2014 mark was the highest of his career, just a shade ahead of the previous two seasons. After posting an unearthly 50.2 percent strikeout rate in 2012, Kimbrel has settled in the high 30s in each of the past two years.
The Braves second-hardest thrower was 27 year-old right-hander Juan Jaime. He made his major league debut and appeared in 16 games, pitching 12.1 innings. While he struck out 28 percent of hitters, Jaime wasn't particularly effective, as he walked nine hitters and allowed eight runs.
Setup men Jordan Walden and David Carpenter brought the heat for the Braves. The 26 year-old Walden previously served as the closer for the Los Angeles Angels. In his 2010 debut his heater averaged just under 99 miles per hour. Now he's at 96 miles per hour, but he's throwing more sliders and changeups, resulting in a higher swing and miss rate.
Carpenter has bounced around, but he appears to have found a home with the Braves, his fourth club. In his two seasons with Atlanta, he's posted a 2.63 ERA and a 27.4 percent strikeout rate. He's added some velocity to his heater with the Braves. His 95.6 average is almost two miles per hour more than what he averaged in his 2011 campaign with the Astros.
Those four arms represent the Braves hardest throwers, but there are more arms in the stable. Rookie Shae Simmons appeared in 26 games and averaged 94.9 miles per hour before a shoulder injury ended his season. Luis Avilan and Anthony Varvaro each appeared in over 60 games and clocked in at just under 93 miles per hour. Only two relief pitchers for the Braves, Gus Schlosser and James Russell, averaged under 90 miles per hour, and they combined for only 38 innings. By comparison, the Royals received just under 100 innings from soft-tossers Francisley Bueno, Louis Coleman, Scott Downs and Bruce Chen, none of whom averaged 90 miles per hour.
Of course, fastball velocity isn't everything. Braves relievers totaled just under 4 WAR calculated by either fWAR or RA-9 WAR. 2.2 of that can be attributed to Kimbrel alone. Meanwhile, Royals relievers produced 5.9 fWAR and 7.4 RA-9 WAR. It's hard to imagine a harder throwing bullpen than the cannons the Royals trot out, but the Braves trumped them.
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Stats courtesy of Fangraphs
Chris Moran is a former college baseball player at Wheaton College and current third-year law student at Washington University in St. Louis. He's also an assistant baseball coach at Wash U. In addition to Beyond The Box Score, he contributes at Gammons Daily. He went to his first baseball game at age two. Follow him on Twitter@hangingslurves.