The 22-year-old Pike was 6-5 with a 4.01 ERA in 25 starts with Class A Advanced Bakersfield last season, with 134 strikeouts and 68 walks in 125 2/3 innings.
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Over five seasons in the Mariners' organization, Pike went 26-26 with a 4.04 ERA in 113 starts. He reached as high as Double-A Jackson twice in 2014-15 and went 3-6 with a 6.90 ERA in 16 starts, but he was kept at Bakersfield for this past year.
The 6-foot, 180-pounder was the 126th overall pick in the 2012 Draft out of Winter Haven High School in Florida.
In return for Jackson and Pike, the Mariners picked up two more advanced pitching prospects in Whalen and Povse. Whalen, 22, made five starts for the Braves in 2016 and was immediately installed as Seattle's No. 14 prospect by MLBPipeline.com.
Povse, 23, was a third-round Draft pick in 2014 out of UNC-Greensboro. Though the 6-foot-8 right-hander split last year between Class A and Double-A, he's seen as a high-upside pitcher and is ranked as the club's No. 10 prospect.
Kiekhefer outrighted to Tacoma
Left-hander Dean Kiekhefer, who was designated for assignment last Saturday to make room on the 40-man roster after the Mariners signed free-agent pitcher Marc Rzepczynski, has cleared waivers and was outrighted to Triple-A Tacoma.
Kiekhefer, 27, was claimed off waivers from the Cardinals on Nov. 4 and provides left-handed relief depth. He pitched in 26 games for St. Louis in 2016 as a rookie, posting a 5.32 ERA in 22 innings over five Major League stints. He also went 6-1 with two saves and a 2.08 ERA in 29 games for Triple-A Memphis.
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.