Toolshed Stats: ISO and prospect power

In addition to our weekly Toolshed column, every Tuesday during the first half of the offseason our new Toolshed Stats series will use advanced statistics such as ISO, FIP, Spd and park factors to better understand prospect performance during the 2016 Minor League season.

The first installment of our new Toolshed Stats series focuses on isolated slugging percentage (ISO), which we derive by simply subtracting batting average from slugging percentage. The higher your ISO, the higher your power. To add some context, David Ortiz led the Majors with a .305 ISO, while Adeiny Hechavarria was last among qualifiers at .075.

For comparison, we'll use the power tool grades provided by MLB.com's top 100 prospect list to see how players' ISO matches up with expectations based on those grades, which work on a 20-80 scale. We achieve this by taking the average ISO and power grade and using their standard deviations to get everything on the same scale. (Among this year's batch of top 100 prospects, the average power tool was 51.7 and average ISO was .172, while the standard deviations were 8.76 and .0472, respectively.) If a hitter's ISO and power grade standard deviations are about the same, then he performed about as expected, given his skill set. If they're wildly different, then we have a talking point.

In that way, one prospect saw a particularly wide gap between his ISO standard deviation and his power grade standard deviation, putting him atop the group we're calling "ISO overperformers."

Ozzie Albies will never be confused with a prototypical power hitter. At 19 years old, the Braves' No. 2 prospect is listed at 5-foot-9, 160 pounds and entered 2016 with one career homer in 155 Minor League games across three levels. But baseball is full of surprises, and it might be time to rethink Albies and his power grade.

In his second full season, MLB.com's No. 13 overall prospect was given a 20 for his power, the only top-100 prospect to receive such a grade in the category and one of only three to receive a grade below 40. According to our formula, if he had lived up to that low bar, his ISO would have been an equal outlier. And yet, Albies' .129 ISO (derived from a .292 average and a .420 slugging percentage over 552 at-bats) was actually about what we'd expect from a 45-grade power hitter, based on standard deviations -- still below average, but far from the bottom of the barrel.

A switch-hitter, Albies launched six homers in 552 at-bats between Double-A Mississippi and Triple-A Gwinnett. That's not an astounding total, but when a player enters the season with only one career homer to his name, six is certainly a notable jump. Add the fact that the power jump coincided with Albies skipping a level to start the season at Double-A, and the jump goes from notable to borderline remarkable.

As it turns out, the Braves didn't even try to get Albies to add power in his second full season.

"There was actually no emphasis on making him hit for power," said Garey Ingram, Albies' hitting coach at Mississippi. "We wanted to make sure his swing was staying short and that he was getting as quick to the ball as possible. He's at his best when he's hitting line drives, so we didn't want him getting in the air as much. At these upper levels, the strike zone can get a little smaller, and that can help some guys make more consistent contact and a little pop can show through. At [Class A], the strike zone isn't as precise and you may have to reach a little more. But up here, when you have a better idea where it'll be and you're trying to make hard contact, there can be some occasional pop."

That type of approach didn't only lead to homers, though. Forty-nine of his 161 hits went for extra bases between his two stops as 10 were triples and 33 were doubles. Though he may not be powerful, Albies is certainly quick on the basepaths with 70-grade speed and a penchant for turning singles into doubles and doubles into triples. With slugging percentage (and thus ISO) being based on total bases, that instinct to grab an extra bag helps him here.

"A lot of times, he was thinking third right out of the box," Ingram said. "Sometimes, guys aren't doing that until they get to first base and then it's already too late. This is the type of kid who wants the extra base every time, and that's the case with triples and doubles. He's such an aggressive runner, and that's obviously what you want on the basepaths."

So it's possible Albies cheated the ISO system slightly in that regard. But the fact remains that a 20-grade power hitter is typically painted as a singles-only slap hitter, and Albies has proven to be more than that. In fact, he was also the biggest ISO overperformer in 2015 when he slugged like a 40-grade power hitter. With a plus hit tool and the opportunity to form a dynamic middle infield next to No. 4 overall prospect Dansby Swanson in Atlanta, he won't need to be any type of slugger to bring the Braves value. But with some room still to grow at 19, don't be surprised if Albies' power tool gets even better as he goes up the chain.

Check out the full table of ISO's and power grades here.

More on overperformers

Not only did Chapman and Meadows finish second and third in beating expectations in the chart above, they also finished in those same spots in ISO overall.

Chapman is growing into one of the classic three true outcome sluggers as he hit 36 homers (third-most in the Minors), struck out 173 times (10th-most in the Minors) and took 68 free passes in 589 total plate appearances (a solid walk rate of 11.5 percent). He'll need to cut down on those K's at the higher levels, but if he can maintain that power against tougher pitching while still providing impressive defense at the hot corner, he has a chance to be a valuable player for Oakland.

Meadows' performance in ISO, meanwhile, was powered mostly by extra-base hits that stayed in the yard. The 21-year-old outfielder's 12 homers were a career high, but like Albies, he used above-average speed to pick up 11 triples and 23 doubles in only 82 Minor League games (335 plate appearances). The left-hander's swing is sweet enough to shoot for the gaps right now, and given his age, he still might grow into an above-average power threat, though he'll have to figure out Triple-A arms first against which he hit .214 with a .757 OPS. He'll also have to stay healthy with a hamstring injury keeping him under 100 games for the second time in three full seasons. He'll have plenty of chances to prove himself, both in terms of power and health, in 2017 at Triple-A Indianapolis, barring any changes in the crowded Pittsburgh outfield.

Lowest ISOs

If you're looking for the biggest disappointment when it comes to ISO, it's No. 3 Reds prospect Jesse Winker. The 23-year-old outfielder is two years removed from a 2014 campaign in which he produced a .231 ISO with 15 homers and 20 doubles in 74 games at Class A Advanced Bakersfield and Double-A Pensacola. But in 2016, he managed only five long balls and a .402 slugging percentage that equaled his on-base percentage in 110 games between Triple-A Louisville and a rehab stint in the Arizona League. Winker, who was given an above-average 55 power grade by MLB.com, has done enough to keep himself in the prospect conversation with a .308 average and a favorable 63/61 K/BB ratio, but seeing as he's stuck in left without much speed, he'll have to bring the power back to carve himself a role over All-Star Adam Duvall in Cincinnati.

On the mark

Did any top 100 prospects hit their power expectations dead-on, with a 0.0 difference between ISO standard deviation and power grade standard deviation? Yes, they were Southern League MVP Tyler O'Neill (60 power, .215 ISO) of the Mariners, Mets top prospect Amed Rosario (45 power, .136 ISO), White Sox 2016 first-rounder Zack Collins (55 power, .191 ISO) and Yankees slugger Aaron Judge (60 power, .219 ISO). Again, full table here.