The Athletics are moving two rentals in exchange for three very interesting pitching prospects, all of whom have bullpen-worthy stuff at worst — and mid-rotation upside at best.

The headliner of the deal, at least as far as upside is concerned, is RHP Grant Holmes. Holmes, who was committed to Florida, was the 22nd-overall pick in 2014 and signed for $2.5 million out of Conway High School in South Carolina. He touched 100 in high school and was one of the draft’s more advanced prep arms with a more mature body and better strike-throwing ability than many of his hard-throwing peers. After signing, he descended upon the AZL, which was clearly already beneath him at the time, and dominated before moving to the Pioneer League for his last few starts of the season.

In 2015, Holmes’ control went backwards and he walked 54 hitters in 103.1 innings for Low-A Great Lakes. Walks have remained an issue this season (43 free passes in 105 innings). Holmes is an above-average athlete and his delivery isn’t overtly violent or difficult to repeat, but his arm action is long and his release point has been inconsistent. Eventually, I think Holmes will throw enough strikes to start though two straight years of serious control issues are officially concerning.

The stuff is great. Holmes was 92-94 mph and touching 95 for me in April and has generally been in that range all year. His fastball moves, a product of his arm slot, and can be unhittable when he locates it. Holmes’ primary offspeed weapon is his curveball which, when he breaks off a good one, looks like a slider’s caricature. It has two-plane, slider shape and slider velociy (about 79-82) but has the vertical depth of a curveball. It flashes plus but is also inconsistent and can tilt in without much bite.

Holmes’ arm speed lends itself to changeup projection. He’s already shown feel for generating movement with it as well as the ability to throw it to right-handed hitters. It generally sits 84-85 and flashes average, though I believe it has more projection than that.

The repertoire is undoubtedly starter-worthy, and for me it projects as that of an above-average #3 or #4 type of rotation piece, but the way Holmes’ command has begun to rot is a little concerning. I’m still willing to bet Holmes figures things out and finds his way into Oakland’s rotation, though, because he hasn’t thrown strikes for two seasons now, the risk that he doesn’t has grown.

Grant Holmes, Tool Profile Tool Present Future Fastball 60 60 Curveball 50 55 Changeup 45 55 Control 40 50 FV — 50

The next piece in the deal is probably the most famous in RHP Frankie Montas. Montas has missed most all of this season because of a recurring rib injury that may require surgery. Montas had a rib removed in February, broke another in late June and had a four- to eight-week timetable for return when that injury was announced.

Montas has flashed starter’s stuff but has had strike-throwing issues of his own throughout his career. His fastball has been up to 102 and he regularly sits 96-99. Montas has issues staying on line to the plate, especially from the stretch, and his strike-throwing suffers as a result. I’ve left some of Montas’ starts thinking he has a chance to be a rotation piece and others resolute in his relieverdom. I think it’s justifiable to continue to run him out there as a starter and hope it clicks — while also expecting it not to. Montas’ arm has been durable despite his past rib and knee issues and he has the secondaries to pitch through a lineup several times, even if he does so inefficiently.

Montas’ slider sits 86-90 and moves more like a cutter. It’s plus, and he can miss bats with it even when he’s not hitting his spots. I’ve seen Montas throw an above-average changeup but it’s generally fringe to average and he’s seldom needed it in shorter stints.

Frankie Montas, Tool Profile Tool Present Future Fastball 80 80 Slider 60 60 Changeup 45 50 Control 40 45 FV — 50

Finally, we arrive at Jharel Cotton. Cotton is from the U.S. Virgin Islands and made the 2016 Futures Game World roster. His out pitch is a Bugs Bunny changeup in the 78-82 mph range that features late dive away from hitters. It’s a plus-plus pitch for me. Cotton was up to 97 in the Fall League last year but generally sits 92-94 with an average cutter in the 87-90 mph range. His breaking ball is below average but Cotton has begun to learn how to use his cutter to finish off right-handed hitters which I think de-emphasizes the importance of his breaking ball.

Cotton is just an average athlete and he has had some bouts with wildness, but I think he’ll throw enough strikes to start and this might end up being the best arm in the deal. I’m more confident that Cotton can start than I am about Montas, and Cotton is much closer to providing big-league value than Holmes.