Power is everywhere this season. Last year, three players topped 40 home runs. Joey Gallo reached that exact number in the fewest games, at 148. So far in 2019, we already have four guys at 40 or more dingers. Christian Yelich (41) has played the fewest games, at 113, while Pete Alonso (40) has registered the most games at 125. Maybe those dudes were bound to hit a lot of homers anyway, so let’s think of some others who might better frame this league-wide power surge.
Eduardo Escobar has 28 bombs in 125 games so far this year, and his previous career-high was 23 in 151 last year. Carlos Santana has 30 bombs and will likely surpass his previous career best of 34. Jorge Soler already has 35 homers in 126 games and will join the 40-homer club soon enough. The league average ISO — or isolated slugging, which measures how often a guy gets an extra base hit per at-bat — is .184. Last year, it was .161.
It’s hard to overstate how massive that jump is. In the previous decade, the biggest year-over-year increases were 12 points between 2015 and 2016; and 15 points between 2014 to 2015. That tracks back to when the ball first changed and then changed again. It also provides some perspective on the influence that yet another new ball could be having on the league this year. I mean, a 23-point jump in league-wide ISO over a single winter is just hilariously large.
How can we even process it? Which player performances do we buy into? I asked some pals if anyone’s done any work on that this year that I could check out, and I got pointed to an August Fagerstrom article on FanGraphs from mid-September 2016. (Thanks, as they say, to the homies.) He looked at every player who had at least 300 plate appearances each in 2015 and 2016, checking the increase in their ISOs and any potential change in their league-adjusted ISO, or ISO+. Fagerstrom found 19 players who were “faking” their power; guys whose ISO+ numbers were coming in lower than their raw ISOs.
In an even crazier offensive environment with the same question as Fagerstrom, I used his framework and found 33 such fakers to this point in 2019. The whole list can be gleaned here, though the top 10 power impostors are below.
| Player | 2018 ISO | 2018 ISO+ | 2019 ISO | 2019 ISO+ | ISO Diff | ISO+ Diff |
| Kyle Schwarber | .229 | 140 | .263 | 139 | +34 | -1 |
| Eugenio Suárez | .243 | 149 | .268 | 142 | +25 | -7 |
| Ian Desmond | .186 | 114 | .209 | 111 | +23 | -3 |
| Jonathan Schoop | .184 | 111 | .205 | 110 | +21 | -1 |
| Nicholas Castellanos | .202 | 121 | .222 | 118 | +20 | -3 |
| Nomar Mazara | .178 | 107 | .197 | 105 | +19 | -2 |
| Nick Ahmed | .176 | 108 | .194 | 103 | +18 | -5 |
| Eric Hosmer | .145 | 89 | .163 | 86 | +18 | -3 |
| Xander Bogaerts | .234 | 140 | .251 | 134 | +17 | -6 |
| Paul DeJong | .193 | 118 | .208 | 110 | +15 | -8 |
This group poses a bit of a conundrum. They’re all average or better regardless of their adjusted numbers this year, save for Hosmer, whose improvements appear to be more the result of league’s tide rising than his own strokes (as was the case three years ago). Some are established veterans while others are a bit younger and offer a layer of intrigue through upside. So who would you want to bet on moving forward, despite the knowledge that they may be playing over their heads right now? Who would you want to stay away from?
Buying In
| Point of Season | ISO | ISO+ |
| Before trade | .189 | 101 |
| After trade | .392 | 207 |
Nicholas Castellanos seems to have a new lease on life after getting traded from Detroit to the Cub at the deadline. Comerica Park’s cavernous outfield can be antagonistic, and our own Daniel Port detailed how critical a move from Detroit could be for his power here before the trade happened. Now we’re seeing it happen before our very eyes. Castellanos has gone from being definitively average to mind-bendingly excellent. We can’t take a player’s most recent three weeks and say that’s who they are now, especially when there hasn’t been a drastic change in approach. That said, it will be fascinating to see if the Ricketts can find enough money between their threadbare couch cushions to re-sign him this winter. It seems like a great opportunity for both parties.
Speaking of opportunity, I also wouldn’t sell short Eugenio Suárez. It feels like his ability to contribute has been doubted for as long as he’s had regular playing time. His wRC+ is down 20 points from last year and he’s got the second-largest fall from raw ISO to ISO+ among qualifiers. These things might make it feel weird to buy in, but he seems to just keep finding ways to adjust and be successful. He’s shown an ability to hit different types of fastballs, a willingness to tweak his stance to optimize his approach, and even has his own Funko Pop! figure. We’re at the point with him where if we want to say “I don’t think he’ll be this good next year,” and it becomes true, we’ll probably also have to say “He’s still pretty good.” His contract is cheap, meaning the Reds will continue to have a value-based reason to keep him even if his performance dips; and he still plays half his games in cozy Great American Ballpark.
Bailing Out
| Season | BB% | K% | GB:FB | fWAR |
| 2018 | 7.1 | 19.3 | 1.18 | 1.7 (152 games) |
| 2019 | 8.7 | 17.8 | 1.48 | 2.9 (126) |
On the flip side, Nick Ahmed has turned into twice the player by fWAR, but his ISO+ this season is still registering five points less than his 2018. His walks are up and his whiffs are down but it could be that his grounders are cause for concern. He’s hitting nearly 1.5 grounders for every fly ball. Maybe he has a sense he’s playing into the relatively new, humidor-driven environment at Chase Field, or maybe it’s a less conscious thing he’s not even thinking about because it’s working, but asking how long it will last would be fair. In a league that’s rewarding balls in the air more than ever, he’s putting them on the ground at a clip nearly 30 points higher than league average, which is a habit that he’s leaned into more often than not as a major leaguer.
Looking only at raw ISO, Paul DeJong appears to be adding incremental power to his game over the last couple of years. This year, though, his ISO+ tells us it’s not really pacing with the league’s increase in offense. He’s putting the ball in the air, with 1.13 fly balls to every grounder. That looks great, but he’s got the second-fewest batted balls of this group hit at 105 mph or better. Only Ahmed has fewer than that, but putting the ball in the air so much more at a softer rate probably hurts more than it helps. It’s possible he looked like he was aging into a quiet, Marcus Semien-like breakout, but I wouldn’t bet on it.
ISO+ in this context isn’t a death knell. However, it is a tool to keep in our back pockets to help us navigate the shades of gray that abound throughout baseball. Proceed with caution, use with care.
(Photo by Kyle Ross/Icon Sportswire)
I’ll say this up front: I may just not be understanding the premise/point of this article, and if so I apologize.
But I *think* the entire argument is flawed. The difference in ISO and ISO+ shows how a player has performed relative to the current league environment, not in a vacuum. This is useful for comparing the power of players from different eras, seasons or leagues. You would not want to compare a player’s power from 2019 with a player from the 1980s without league context. For example, the ISO+ tells us that hitting 50 bombs this year might not mean a player has had a historically great power season based on the context of so many balls flying out of the yard this year.
But the discrepancy between ISO and ISO+ says nothing about if their raw performance *this year* was “fake.” It does not in any way describe or mean they did not deserve the counting stats they have compiled. What might do that is something like xISO (not sure if that exists) based on inputs that are descriptive based their actual batted ball performance (barrel%, Hard%, launch angle, FB%, Pull%, exit velo, fly ball distance, BABIP, etc.).
Comparing players across eras is certainly a feature of plus stats, but it’s not their sole premise. It’s why using wRC+ is usually more useful than just wRC, regardless whom is being compared when. It lets us worry less about statistical noise. ISO is similar, and this was more a thought experiment about how raw ISO increases compare to ISO+ than it was saying what a player “deserved” like xstats do.
The title of the article is which hitters are “faking their power.” There are then fantasy recommendations predicting future performance or reliability based on differences between ISO and ISO+. I think you’re using that stat wrong.
The idea of “faking” power is more a tongue-in-cheek continuance from August’s article than an endorsement of a black and white buy/sell. My ideas and work tend to range in a continuum of gray, and I’m not sure we’re approaching the piece the same way. That said, I’m happy you’re comfortable enough in the community to comment, and I’m thankful you’re reading. Hope you got something out of it and that you stick around.