The Seattle Mariners made a few moves Friday, placing left-hander Wade Miley on the 15-day disabled list (shoulder) and designated for assignment right-hander Steve Johnson. Replacing the pair on the roster are left-hander David Rollins and right-hander Jonathan Aro. The club expects to soon call on Bellevue native Adrian Sampson, likely to start in place of Miley Saturday.

Here’s what to expect from the trio:

Jonathan Aro, RHR
Aro, 25, has sat in the 89-92 mph range for most of the season in Triple-A Tacoma. At times, he reached back for 94-95, and that’s the pre-2016 scouting report on the fastball. There’s some sink on the pitch in the lower part of the velocity range and some arm side run in the upper half of the velocity range. Aro also offers a fringe-average changeup with some sink, but little fade and he has trouble commanding it. The right-hander’s breaking ball is a low-80s slider with short break, but due to a high arm slot the movement is vertical, limiting the swing-and-miss rate.

Aro will typically throw strikes — nine walks in 33 innings for Tacoma — but he’s not overpowering and will have to locate well to get outs consistently in the big leagues. Neither offspeed pitch is consistently major-league quality, but both flash such.

The high arm slot also limits the margin for error; if Aro doesn’t finish out front, the pitch flattens out and/or is left up in the zone. He simply doesn’t throw hard enough to get away with that.

David Rollins, LHR
We’ve seen Rollins, the former Rule 5 pick. Not much has changed stuff wise; he’s still 90-95 with the fastball to set up a slider, but he’s commanding both pitches better and is more consistent creating advantageous angles versus left-handed batters. Rollins has yet to walk a batter in Tacoma over 26 2/3 innings, a span of 96 batters faced.

Beyond the raw walk totals — or complete lack thereof — Rollins has absolutely pounded the strike zone so far this season. Through his last appearance earlier this week versus Salt Lake, Rollins has thrown 75.4 percent of his pitches for strikes, called, fouled, put in play or swing-and-miss combined. That’s remarkable.

He’s limited lefties to 9-for-48 (.188 AVG, .333 SLG) and righties to 10-for-43 (.205 AVG, .438 SLG). Unlike a year ago, Rollins appears ready to handle a shot in the big leagues.

Adrian Sampson, RHS
Sampson, a Skyline High School product, toes the slab from the third base side and attempts to work left-handed batters away with a fastball sitting 88-93 mph, throwing from a three-quarters slot. There’s late arm side ride 91-93 mph and occasionally some sink when he pulls through the pitch.

Sampson’s changeup is fringe-average but he will throw it to keep hitters honest. His best pitch is a 55-grade slider that has been above-average-to-plus for entire starts this season, so perhaps it’s time to call it a 60-grade pitch. It’s firm at 83-86 mph and while the break is a bit short, it’s late and sharp and Sampson does a good job locating — down and in versus lefties for swings and misses, scraping the outer edge away for called strikes, and cutting away from right-handed batters.

Sampson will pitch by design up in the zone to change the eye level and will throw strikes; expect the strike throwing to continue in the majors, even if he’s getting knocked around a bit. He believes his stuff is good enough to get outs and isn’t afraid to throw any pitch in any count to any hitter.

He’s a No. 5 starter despite two 50-55 pitches and a 40-45 third offering because the command still grades fringe-average and he tends to miss middle in to lefty bats. He’s at his best when he uses the two-seamer on the inner half against lefties and has his best slider.

Jason A. Churchill

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