Statcast Projected Isolated Power Performance in Predicting 2017 Performance

Last February, I took Statcast batted ball data to project Isolated Power performance.  The idea was that big in game power comes from hitting the ball hard and barreling up on it.  I lacked launch angle data, but considered batted ball types.  However, incorporating ground balls, fly balls, and line drives did not improve the model.  Regardless, a model knowing only average distance and barrel per at bat, you could fairly accurately predict Isolated Power performance.  Therefore, if a player underperformed according to the projection then you might expect a bounce back the following season.  However, I wondered whether there were reasons why a player would typically under or over perform the projection.

Looking at the 2016 season, it found the following players whose actual 2016 ISO was the most underperforming in comparison to the model projections:

	2016 ISO	2016 xISO	Diff
Miguel Cabrera	.247	.295	-.048
Josh Harrison	.105	.147	-.042
Brandon Belt	.199	.239	-.040
Howie Kendrick	.111	.149	-.038
Kendrys Morales	.204	.242	-.038
Buster Posey	.147	.184	-.037
Albert Pujols	.189	.226	-.037
Alex Gordon	.160	.197	-.037
Adeiny Hechavarria	.075	.109	-.034
Yonder Alonso	.114	.147	-.033
Troy Tulowitzki	.189	.222	-.033
Nick Markakis	.129	.161	-.032
Mitch Moreland	.189	.220	-.031
Yadier Molina	.120	.151	-.031
Adam Jones	.171	.201	-.030

Looking at this data, Kendrys Morales jumped out to me.  He was quickly scooped up by the Blue Jays in what seemed like a fairly curious move.  He had been a decent hitter for the Royals, but was not doing anything incredibly productive.  His lack of position also hurt roster flexibility.  A three year deal for a player like that seems a bit like folly.  At the time of looking at this model, I thought well maybe the Blue Jays think his ISO underperformed because of Kaufman Stadium.

Mid-season, you heard similar things about Adeiny Hechavarria when the Rays traded for him.  He was hitting the ball hard and barreling it, so perhaps the Rays thought they could better channel that into more productive hitting.  Anyway, how did these guys do in 2017 compared to 2016?

	'16 ISO	'17 ISO	Diff
Albert Pujols	.189	.145	-.044
Yadier Molina	.120	.166	.046
Miguel Cabrera	.247	.149	-.098
Kendrys Morales	.204	.196	-.008
Howie Kendrick	.111	.161	.050
Alex Gordon	.160	.107	-.053
Nick Markakis	.129	.110	-.019
Troy Tulowitzki	.189	.129	-.060
Mitch Moreland	.189	.197	.008
Adam Jones	.171	.181	.010
Buster Posey	.147	.142	-.005
Yonder Alonso	.114	.235	.121
Josh Harrison	.105	.160	.055
Brandon Belt	.199	.228	.029
Adeiny Hechavarria	.075	.145	.070
		32+	-.020
		31-	.047
		All	.010

One thing you will notice is that I reordered them by age.  Moreland and up are 2017 seasons played as 32 or older.  Jones and down are age 31 and younger.  What this paltry little sample seems to suggest is that underperforming your expected ISO is a major red flag for players in the mid to late 30s.  It is indicative of something else happening that is eroding performance.  However, for younger players, who are in less of a decline phase age-wise, show significant rebounding in performance.

What does this mean going forward?  Below are the players who most underperformed their expected Isolated Power performance:

Player	2017 ISO	2017 xISO	Diff
Miguel Cabrera	.149	.230	-.081
Mitch Moreland	.197	.248	-.051
Alex Gordon	.107	.157	-.051
Kyle Seager	.201	.248	-.047
Jose Peraza	.066	.113	-.047
Justin Turner	.208	.252	-.044
Matt Carpenter	.209	.250	-.041
Nicholas Castellanos	.218	.258	-.040
Jed Lowrie	.171	.209	-.038
Alcides Escobar	.107	.144	-.037
Albert Pujols	.145	.180	-.035
Chris Davis	.208	.241	-.033
Shin-Soo Choo	.162	.194	-.032
Dansby Swanson	.092	.124	-.032
Ian Kinsler	.176	.207	-.031
Jose Bautista	.164	.195	-.031
Hanley Ramirez	.188	.218	-.030
Nick Markakis	.110	.140	-.030
Yadier Molina	.166	.196	-.030
Joe Mauer	.112	.142	-.030

What we see above in this list is a lot of older players who failed to live up to the projections.  If the 2017 data is indicative of anything, this does not bode well for most of these guys.  Younger players on the list are a mix in availability like Nick Castellanos are supposedly available in trade or like Dansby Swanson are not available.  It is these players who we might expect as they age they refine their skills and are able to turn their barreling and distance into something more useful.

Chris Davis, for the Orioles interested readership, will be entering his age 32 season.  Above, that barely places him into the upper range that saw a major erosion in performance.  Molina and Kendrick were really the only two players who bounced back.  The others treaded water or further collapsed.  For those hoping for Davis to reclaim his past greatness, it is a weak indicator that perhaps that simply is unlikely to be in the cards this upcoming season.