Last season, his third with the Royals, Collins went 3-6 with a 3.54 ERA in 66 games (53 1/3 innings). He was especially effective after the All-Star break as the Royals made a Wild Card run, posting a 1.35 ERA and working nine scoreless innings between Aug. 26 and Sept. 23.
His best work came outside the American League Central, with a 1.53 ERA over 35 1/3 innings. Inside the division, however, he gave up 15 earned runs in 18 innings, for a 15.00 ERA.
Collins finished just two relief appearances shy of closer Greg Holland's club high, 68. He had 52 strikeouts, for a career total of 205, ninth all-time among Royals relievers.
With the Collins agreement, the Royals have six unsigned players eligible for arbitration -- first baseman Eric Hosmer, infielder Emilio Bonifacio, outfielder Justin Maxwell, and pitchers Holland, Aaron Crow and Luke Hochevar.
Catcher Brett Hayes signed a one-year deal for $630,000, plus $20,000 in performance bonuses.
There could be more signings on Friday, the deadline for clubs and players to exchange salary figures.
The arbitration process is generally for players who have at least three years of Major League service but fewer than the six needed to qualify for free agency. Select players who have between two and three years of service also qualify as "Super Twos," which was the case this year for Hosmer.
Whereas players with fewer than three years' service have their salary set by the clubs, arbitration-eligibles are paid relative to similar players in terms of performance and service time, as provided by the Basic Agreement between Major League Baseball and the Players Association. Various factors are considered by the club and the players' agents, and each side determines a figure.
After those figures are exchanged, the parties can continue negotiating until the date of an arbitration hearing, between Feb. 1-21. Most cases are settled before a hearing.
If a case does reach that phase, a three-judge panel listens to both sides and picks one figure or the other, nothing in between. General manager Dayton Moore has never had a case go all the way to a hearing during his watch, which began with the 2007 payroll.