Keep in mind that this is not a traditional top prospect list because it focuses entirely on 2014 contributions. I rank guys according to advanced metrics which, for position players, include batting runs above average (now from Fangraphs), positional adjustment, and a replacement level calculation that scales the total to "Wins Above Replacement" (though the concept of replacement level doesn't really apply to minor leaguers, obviously). Defense is a best guess, though I'd like to think it's an informed one. I use a standard "runs allowed based" WAR formula for pitchers for the ranking, but include FIP-based WAR for comparison.
13. Andrew Heaney, 23, AAA. RA-9 WAR: 2.8, FIP WAR: 3.5. 3.78 ERA / 23.5% K-rate / 6.2% BB-rate
The Halos' new top prospect had an interesting season, defined primarily by pronounced splits. Major league righties mashed .309/.364/.580 against him, but more on that in a moment. Heaney mowed down lefties, including major leaguers, fanning 29% while walking only 5% with a straightforward down-and-away fastball/slider approach. When same-handers did manage contact, they pounded the ball into the ground at a 63% rate. Even when they got the bat head out in front to pull, it was all they could do to roll over to the right side of the infield 87% of the time. That's dominance.
If you're curious about how that performance against left handed hitting stacks up against Heaney's peers, here's a breakdown of his component stats in percentile form, courtesy of ‘reillocity,' a contributor at www.minorleagueball.com:
(Number is percentile rating vs League SP (100:best, 50:average, 0:worst))
Against [Lefties]: 99th [Overall], 82nd [Control], 99th [K-rate], 89th [Batted ball profile]: 97th GroundBall, 26th Infield Fly Ball, 31st line drive avoidance, 99th Outfield Fly ball Avoidance, 97th Pulled-3rd OFFB Avoidance [not entirely sure if this incorporates anything beyond pulled fly balls])
Even if he doesn't make the rotation--which he may not, given the competition--he could break into the majors as a dominant bullpen piece that helps to leverage the Halos into October. Don't get me wrong: Heaney has the tools to be a starter long term, but in the coming year, his greatest value to the major league club might be as a shutdown lefty killer.
Heaney has more work to do against opposite handers, which explains, at least in part, why the Halos wound up with him. His K/BB ratio remained consistent from 2013 to 2014, but advanced righties showed a more pronounced propensity to drive fastballs hard to the middle of the field. In the majors, Heaney's heat maps reflect an attempt to use the same down and away approach that so dominated same-handers, but MLB righties preferred not to reach beyond the outer half like lefties did. Instead, they waited out mistakes, and Heaney obliged, leaking enough fastballs back up and over the plate to take a .321/.628 (avg/slf) beating on contact. The slider remained tough,and early returns on the change-up were promising in the small major league sample witnessed by PitchF/x. The strong secondaries just didn't matter at the MLB level because Heaney couldn't establish his fastball.
This is a lot of data to throw at you, but I'm trying to decide what's important. Remember, Heaney was an Andrew Friedman asset, however briefly, and an asset that the new Dodgers executive chose to part with. Heaney has a great pitch in his slider, which alone should provide value to the Angels, perhaps in relief appearances in 2015. His long term value, however, will depend on how good he becomes at sequencing and spotting his fastball and change-up against righties. 2014 was a bit worrisome in that regard.