KANSAS CITY, Mo. - The Royals and reliever Kelvin Herrera agreed on a $4.15 million, two-year deal Thursday that leaves only first baseman Eric Hosmer and closer Greg Holland among the American League champions' unsigned, arbitration-eligible players.

Herrera will make $1.6 million this season and $2.55 million next season, and can earn up to $250,000 in performance bonuses, a person familiar with the deal told The Associated Press. The person spoke on condition of anonymity because the terms were not disclosed.

The 25-year-old Herrera, who primarily handles the seventh inning, made just $522,250 last season and was eligible for arbitration for the first time. He filed for $1.9 million for this season and the Royals countered at $1.15 million.

Royals pitchers and catchers are due to report next week to Surprise, Arizona.

Herrera was likely to earn a significant jump in salary given his breakout season. He had a 1.41 ERA over 70 appearances, fifth-best among big league relievers. He was especially good over the second half as the Royals made a run to the World Series, going 31 innings without allowing a run between June 27 and Sept. 16 — the second-longest streak in the American League.

With a maximum-effort delivery that produces a blazing fastball, Herrera also did not allow a home run last season, extending his streak to 95 straight innings dating to July 28, 2013.

The Royals have spent lavishly to keep their shutdown bullpen intact this off-season.

They exercised their option on setup man Wade Davis, which means he'll earn $7 million this year and now has an $8 million option for 2016 with a $500,000 buyout. And they gave a $10 million, two-year deal to Luke Hochevar, who missed last season after undergoing Tommy John surgery.

Then there's Holland, who could become a free agent after next season. The All-Star closer made $4,725,000 last season and filed for $9 million, while the Royals offered $6.65 million.

Holland had a 1.44 ERA with 46 saves in 65 appearances last season.

Hosmer, who made $3.6 million last season, asked for $6.7 million after hitting .270 last season and earning his second Gold Glove. The Royals offered him $4.6 million.

If the Royals cannot reach an agreement with Holland or Hosmer, it would be the first time since general manager Dayton Moore was hired in 2006 that a player went to arbitration. Already, players and teams have split six decisions that have gone before a three-person panel.