Brandon Sean Michael Brennan
Height: 6'4" Weight: 220
Bats/Throws: Right / Right
Born: 07/26/1991 in Mission Viejo, California
Offseason home: San Juan Capistrano, California
College: Orange Coast College
Acquired: Selected in the Rule 5 draft from the Colorado Rockies (12/11/2018)
MLB Debut: 03/21/2019
Free Agent after: 2024 season
The Mariners tried to sign Brennan as a minor-league free agent over the offseason, but lost out on him to the Colorado Rockies. No matter—Colorado left him off their 40-man roster and thus the M's could claim him via the Rule 5 draft. That method requires the M's to keep him in the big leagues all season, but given (a) his performance so far and (b) the performance of certain others in the bullpen, that doesn't appear to be much of a challenge.
The hard-throwing right-hander has been impressive in the early going. Over the first homestand and the opening two games in Japan, Brennan has thrown six scoreless innings with ease, outperforming any reasonable expectation for someone who'd never pitched above Triple-A before. He spent seven years as a White Sox farmhand, splitting the last two between Double-A and Triple-A. His numbers at Triple-A Charlotte were respectable—1-1, 3.57 ERA—but in only 222⁄3 innings. With such a sparse record at high levels of play, it's difficult to predict continued success for Brennan, but as we've already seen, he certainly has the stuff to do so. He was starting games until 2016, but finally earned a promotion past Class-A ball when he shifted to a relief/swing role. The White Sox are not well-regarded in terms of their player development and it may simply be that Brennan was shortchanged with so much time in the lower minors; the M's certainly think his three-pitch repertoire and mature emotional makeup is worth the gamble of throwing him in the proverbial deep end.
Brennan can certainly get a strikeout when needed, but he also tends to induce plenty of grounders, so infielders need to be on their toes when he's on the mound.