By Eric Longenhagen

The Miami Marlins are a bit of a surprise, sitting just 1 1/2 games out of first place in a very mediocre National League East after losing to the Cubs on Wednesday afternoon. That they're still contending right now without the aid of injured young stud Jose Fernandez is a surprise, and in his absence the Marlins have struggled to patch together a rotation they find acceptable. These struggles have led to the recent exile of both Kevin Slowey and Randy Wolf and subsequent promotion of the 2012 draft's ninth overall selection, Andrew Heaney.

The former Oklahoma State Cowboy has ascended through the minor leagues at a torrid pace, posting a 2.47 ERA between Double-A and Triple-A this year prior to his callup. In the just over two calendar years since he was draftted, Heaney has risen to the top from rookie ball, a meteoric rise by anyone's player development standards. The 6-foot-2, 190-pound lefty has a fine pitcher's body, throwing from a low three-quarters arm slot and, while the arm action is a tad long and there's some dirt in the way his arm works, he repeats his delivery well and keeps his head still and on target throughout, which allows him to pitch with average to above average control and command.

While Heaney's stuff isn't electrifying, it's certainly good enough to do damage at the major league level. His fastball velocity can fluctuate heavily; I've seen Heaney start games in the 87-91 mph range, then settle in around 90-93 mph and reach back for as much as 95 mph when he needs it. Reports indicate that he has topped out at 97 this year. While generally it's a plus fastball on velocity alone, Heaney squeezes a little more out of it thanks to the natural movement he gets on the pitch. Heaney's lower-than-average arm angle allows him to generate more horizontal spin on the pitch, thus creating armside run.

Heaney's best secondary offering is a slider that is truly a plus offering, one that will miss bats at the highest level. The slider arrives in the 77-83 mph range with two-plane tilt. Heaney will back-door the pitch to righties early in counts, bury it to their back foot to get swings and misses, and of course run it away from lefties when he gets ahead. When he misses with it, it's often down in the zone or in the dirt, which helps mitigate the anecdotal, homer-prone concerns a lot of scouts have with slider-heavy pitchers. Bad sliders get hit a long way, but Heaney doesn't throw many of them.

Heaney's changeup (79-84 mph when I last saw him) is a bit behind his other offerings but is still going to be a useful weapon. He knows how to release and spin the pitch to get good downward tumble on it and he maintains his fastball arm speed, but the length of his arm action makes the pitch (and all of his pitches) a little bit easy for right-handed hitters to identify out of his hand. Potential platoon issues might be counterbalanced by Heaney's fastball, which gets on you much quicker than his simple, easy delivery would lead you to believe. It's possible, after hitters are beaten by the surprising burst of Heaney's fastball a few times, that they gear up for it their second or third time through the lineup and wind up flailing at his changeup based on consistent arm speed alone. The changeup is an average pitch in a vacuum, but its ultimate utility depends on Heaney's sequencing and any future adjustments he makes to hide the ball differently.

The all-encompassing projection here is very favorable. Heaney's profile is that of a high-end No. 3 starter, thanks to the plus fastball that could grow into a grade 65 pitch if he finds a way to maintain higher velocities for longer stretches, a plus slider and an average changeup that has room for growth.

With Heaney up, the future of the Marlins rotation looks incredibly bright. Tommy John success rates are high enough that it's OK to be cautiously optimistic about Fernandez's return to dominance, though he'll still almost certainly miss a big chunk of 2015. Henderson Alvarez doesn't have swing-and-miss stuff, but he throws hard and generates a ton of ground balls (his 53.8 percent ground ball rate is tied for 14th in MLB this year). Nate Eovaldi, once an arm strength lottery ticket, has learned how to pitch his way through a lineup multiple times without using a changeup. You take those four arms and hope that either Jacob Turner or Tyler Kolek (last week's No. 2 overall pick) turns into something and you have one of the more effective rotations in baseball on your hands. That, plus useful young talent in Christian Yelich, Adeiny Hechevarria, Marcell Ozuna, Jake Marisnick and whatever prospect booty Miami plunders in a Giancarlo Stanton deal, makes the Fish a very interesting team to watch.

Heaney debuts at home on Thursday night against the Mets and another young pitching star in Zack Wheeler in what is a must-see game for any baseball fan with the future in mind.

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Eric Longenhagen hails from Catasauqua, Pa., and has been working in various baseball capacities since his freshman year of college in 2007, including work in the minor leagues, at Baseball Info Solutions and most recently scouting and writing for CrashburnAlley.com and ProspectInsider.com.