With both newcomers immediately being targeted for a 40-man roster at full capacity, two trims had to be made -- and Garrett Jones was designated for assignment, along with right-hander Kyle McPherson.
Jones, the popular and powerful first baseman-outfielder, was already a prime candidate to not be tendered a contract at next Monday's deadline. So in that regard, the decision to DFA was a mere technicality for the 32-year-old left-handed hitter, priced by service time out of the Pirates' range.
"Garrett is a victim of the arbitration process," Pittsburgh general manager Neal Huntington said. "His salary would be predetermined by comparable performances on the market, and we expected it to rise to a level we're not comfortable with. We had already decided to trade or non-tender him."
The DFA process still leaves the Pirates with a 10-day window to work out a trade for Jones, who is eligible for salary arbitration for the third time, and a year ago negotiated a contract for $4.5 million.
In 4 1/2 seasons with the Pirates, Jones totaled 100 home runs and 325 RBIs while batting .256 in 677 games. He had 15 homers and 51 RBIs last season, when he was displaced at both of his defensive positions in September by the acquisitions of right fielder Marlon Byrd and first baseman Justin Morneau.
McPherson, 26, was a candidate for the Pirates' rotation in Spring Training, but he came down with an elbow injury that led to Tommy John surgery on July 10.
Dickerson, 23, the Eastern League Rookie of the Year in 2013 after batting .288 with 17 homers and 68 RBIs for Double-A Altoona, ironically is another player in Jones' mold: A lefty-hitting first baseman-right fielder.
With Gregory Polanco their prime outfield prospect on the horizon, the Pirates were willing to swap Dickerson for two players who provide depth for anticipated future moves to come.
Mikolas, 25, made a solid Major League debut with the Padres in 2012, and last season ranked as one of the top closers in the offensive-oriented Pacific Coast League. At Triple-A Tucson, he had 26 saves in 54 appearances, allowing 22 earned runs in 61 innings.
Decker, 23, joins the Pirates' cache of former No. 1 Draft picks. A supplemental selection (No. 42 overall) in the 2008 First-Year Player Draft, Decker has stalled in the Minors after starting his pro career by being named the top player in his league the first two years.
In six Minor League seasons, Decker, a 5-foot-10, 190-pound left-handed batter, has hit .268 with good gap power. Despite a modest total of only 71 home runs, he has a career OPS of .858, thanks to the plate discipline reflected by an on-base percentage of .402.
"He commands the strike zone well and sprays the ball," Huntington said. "Both players add depth. They have a chance to make the club on April 1, or if not, help us at some point this season."