Welcome to another edition of “Positive & Negative Regression.” Each week we’ll dig into some analytics to identify two players due to heat up and two who are likely to cool down.
This week, we’ll focus on ISO (isolated power) and its Statcast cousin xISO. If you are unfamiliar with ISO, the formula is simply SLG – BA. ISO measures raw power, and thus you would expect players with high ISOs to be productive fantasy players. This is obvious for home runs, but high ISO batters should also be strong contributors for runs and RBI. After all, doubles and triples are more likely than singles to generate production in these categories.
Let’s take a look at the ISO leaders for 2021 (minimum 500 PAs):
| Player | PA | ISO | HR | R | RBI |
| Shohei Ohtani (SP, DH – LAA) | 639 | .335 | 46 | 103 | 100 |
| Fernando Tatis Jr. (SS, OF – SD) | 546 | .328 | 42 | 99 | 97 |
| Bryce Harper (DH, OF – PHI) | 599 | .305 | 35 | 101 | 84 |
| Joey Votto (1B – CIN) | 533 | .297 | 36 | 73 | 99 |
| Vladimir Guerrero Jr. (1B, DH – TOR) | 698 | .290 | 48 | 123 | 111 |
That’s a pretty good list! However, how do we use ISO to help us with our 2022 fantasy teams? ISO is a descriptive stat and thus probably won’t allow us to predict future production. That’s where xISO comes in. Just as we often use xBA vs. BA to determine which players are likely to see their average rise or fall, we can compare xISO to ISO to estimate positive and negative regression.
Below are two players whose xISO is much higher than their ISO and therefore are due for some positive regression. In addition are two hitters who risk some negative regression as their metrics are reversed. The table below each name displays their 2022 stats through June 4.
Positive Regression Candidates
| PA | HR | RBI | R | AVG | ISO | xISO |
| 152 | 5 | 7 | 13 | .173 | .128 | .252 |
ISO doesn’t gloss over the fact that Gallo’s BA is .173, and his xBA is only slightly better at .198. His BA will drag you down, but he was supposed to make it up in the other categories – especially HRs, which hasn’t happened yet in 2022. However, there are some indications that Gallo may be able to turn it around in the power department. His xSLG is .450, while his SLG is only .301. That drives the ISO/xISO variance and why the HRs may start coming. He’s hitting the ball hard when he makes contact; he just hasn’t seen the results yet.
Many frustrated fantasy managers have moved on from Gallo, so there’s a good chance he’s available on your waiver wire. If you are desperate for power and can afford the hit to your average, he may be worth a flier.
| PA | HR | RBI | R | AVG | ISO | xISO |
| 238 | 4 | 30 | 34 | .291 | .160 | .274 |
Freeman’s batting average, RBI, and runs scored are fine – but four home runs? Like Gallo, the SLG/xSLG variance is quite large, so it is likely he’s just been a bit unlucky. His 6.2 % HR/FB ratio reflects this, as he’s never been below 14% in his career. His Hard Hit and Barrel %’s are also in line with his norms.
This data makes Freeman an excellent buy-low candidate if his fantasy manager is getting antsy. Freeman looks as good as ever and could be in for a big second half.
Negative Regression Candidates
| PA | HR | RBI | R | AVG | ISO | xISO |
| 210 | 14 | 53 | 33 | .298 | .348 | .245 |
Ramirez is off to a fantastic start, and he is a true fantasy stud, so don’t take this the wrong way. He’s not going to suddenly crater. However, he is likely to slow down. His batting average doesn’t vary too much from his xBA, but his SLG is +.110 to his xSLG. This colossal variance gives him the largest ISO to xISO gap in the league by a wide margin (minimum 150 PAs). Ramirez’s Hard Hit and Barrel %’s are actually slightly down from 2021, so it doesn’t appear he’s doing anything dramatically different.
Ramirez will continue to produce excellent fantasy numbers and will likely be among the top hitters in the league again this year when all is said and done. However, if he’s on your roster and you get an amazing trade offer for him, think twice before rejecting it. Conversely, if you seek to add him via trade, temper your expectations of what he may give you in return.
| PA | HR | RBI | R | AVG | ISO | xISO |
| 165 | 10 | 17 | 24 | .265 | .245 | .203 |
Altuve’s numbers are slightly different from the other three we’ve reviewed. His xBA is quite a bit higher than his BA, while his xSLG is marginally lower than his SLG. Thus he may be a better hitter than what he’s shown so far in 2022, but with less power. A quick look at some of his other metrics supports this notion. His HR/FB rate of 23.8% is very high, indicating that the home run rate may slow down. Conversely, his .247 BABIP is well below his norm, and thus you can expect his BA to climb.
Altuve’s overall value may not change from a fantasy perspective, and we may just see his profile shift from a power hitter to an average hitter. So if he’s on your roster, plan accordingly. If you need the power, you may want to look elsewhere. However, if a higher BA would be a welcome change, sit tight as you may be in luck.
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