Zych (biceps) threw a 25-pitch bullpen session Friday, in which he increased his intensity from his previous exercise, Ryan Divish of the Seattle Times reports.
The right-hander, who boasts a career 2.81 ERA with 45 strikeouts and only 13 walks in 32 innings, might return to major league action sometime early in the season. He has the stuff to enter the closer picture eventually, but until further notice, he'll set the table for Mariners stopper Edwin Diaz when active.