SAN DIEGO – The success of the Royals’ deep bullpen is being felt on the free-agent market.

In recent years, teams had been ebbing away from paying relievers significant dollars, feeling they were the easiest pieces to find inexpensively. However, Kansas City’s run to the World Series behind a dominant trio of late-game relievers – Kelvin Herrera, Wade Davis and Greg Holland – has convinced more teams to try to invest in this area.

For the first time since after the 2007 campaign, two relievers in the same free agent class received more than $35 million: Francisco Cordero (four years, $46 million) and Mariano Rivera (three years, $45 million) then, Andrew Miller (four years, $36 million) and David Robertson (four years, $46 million) now. It also represents the first time since that offseason two relievers got four-year deals (Cordero and Scott Linebrink).

There were no contracts of four years last offseason for relievers and three of three years (Boone Logan, Joe Smith and Javier Lopez). This offseason, Miller, Robertson, Zach Duke and Luke Gregerson already have received deals for three years or more.

Gregerson reached agreement Tuesday for three years at $18.5 million with the Astros, who also inked Pat Neshek for two years at $12.5 million. Houston clearly saw this as a Royal path to spend to improve without taking significant long-term financial risk.

Gregerson is the only active reliever with at least 60 appearances and an ERA of 3.25 in each of the past six years. Astros general manager Jeff Luhnow was in charge of the Cardinals draft when they selected him in 2006. The Astros’ new manager, A.J. Hinch, ran pro scouting for three years in San Diego while Gregerson was there.

Neshek, 34, had his healthiest/best season last year for St. Louis, going 7-2 with a 1.87 ERA and six saves.