• Seattle starter Brandon Maurer doesn't get the attention of the Mariners' "big three" pitching prospects, but at this point I think he's already passed the third of that group (discussed below), and the right-hander should be considered a future member of the team's big league rotation.
Maurer worked mostly at 91-94 mph on Thursday, but it was the plus slider, with excellent tilt, that was the real separator for him; that pitch was mostly 83-85 but he threw one at 87 that could have gotten him arrested, and he was freezing right-handed hitters with the slider for much of his outing. He showed a hard-fading changeup in that same velocity range, an average pitch but one he sells well and will throw repeatedly to lefties, three times in four pitches in one sequence. His curveball was the one below-average pitch, as he couldn't get a consistent release on it.
Maurer has had a lot of injury trouble in his career; 2012 was the first time he topped 80 innings in a full season, and he's had both elbow and shoulder problems since signing in 2008. The delivery isn't pretty, but there's nothing inherently awful about it, as he pronates early enough and his arm is in position when his front leg lands.
It's not an especially quick arm, and there may be some extra stress on the shoulder because of that, but even if that's the case there's not much to be done about it. If the Mariners want to give Taijuan Walker and Danny Hultzen (who's missed a few days with a strained hip flexor) more time in the minors this year, they might look to Maurer first as a call-up, since he's pretty good in his own right and may not have as many bullets in his arm as the other two.
• Mariners lefty James Paxton -- the third of the "big three" along with Walker and Hultzen -- was awful, facing seven batters, walking two and leaving after retiring just two batters when he was probably scheduled to get six outs. He had no command and his fastball was mostly 89-91, touching 93. Paxton also had a lot of trouble throwing his changeup, releasing it too hard and early for greater velocity but less action (that is, no action to speak of). He barely used his curveball because he couldn't get to appropriate counts for it. You can get away with diminished command when you have better velocity, or with diminished velocity when you have good command, but in this particular outing Paxton had neither.
• Seattle infielder Brad Miller has drastically shortened his swing since I last saw him a few years ago, keeping his hands about even with his shoulder when he sets up and only bringing them a touch back when he loads -- as opposed to his old swing where his hands were back above his left ear when he finished loading them. There isn't much power in this new swing, but it should allow him to maintain the good contact rate he showed last year after he reached Double-A. With his above-average defense at either middle infield spot, the 23-year-old has a good shot to be an everyday player for someone, maybe even a good one.