Baseball is a game filled with unexpected outcomes. Filtered between these unexpected outcomes are plenty of things we can expect. We can expect Max Scherzer to strike out a plethora of batters. We can expect Edwin Diaz to notch a save. We can expect Khris Davis to hit .247. Most of the time, we are all right on these things.

Among these expected outcomes in baseball are our expectations for players put in tougher situations against tougher competition. For example, we can expect hitters coming up from Triple-A to see a dip performance, the same going for hitters. Again, most of the time this comes to fruition. It’s all simple logic.

Going against this logic perhaps than anyone else in recent memory was an unheralded first baseman for the Kansas City Royals, Ryan O’Hearn. O’Hearn was maybe one of the more impressive hitters in 2018 that you’ve never heard of. There were only seven hitters with as many plate appearances and a better wRC+ than him last season: Mike Trout, Mookie Betts, J.D. Martinez, Christian Yelich, Max Muncy, Alex Bregman, and Justin Turner. That’s it. Across his first 170 plate appearances in the major leagues, he slashed a tremendous .262/.353/.597 with 24 of his 39 hits going for extra-bases.

O’Hearn didn’t completely pop out of nowhere. An eighth round pick of Sam Houston State in 2014, he teared his way through the lower-minors, making his way to Triple-A in a matter of three seasons. He’s always been on the Royals radar, and he’s always been on scout’s radars.

That success took a hiatus though once he reached Triple-A. In 869 plate appearances spanning across two seasons, he slashed .243/.324/.423, almost unplayable production for a first baseman, especially considering that he was playing in the high-offensive environment of the Pacific Coast Leaguer. Oddly, his power took a massive dip, caused by a dramatic drop in his HR/FB and BABIP. The lackluster production will still lead to a big league opportunity for him though, with playing time opening up at first base and designated hitter for the sub-par Royals roster.

You’d expect a player in a situation like this to struggle. Forced major league playing time often doesn’t result in a favorable way. But at least there was one reason in favor of O’Hearn’s questionable call-up, his quality of contact skills.

Couple of Reasons for O'Hearn over Schwindel

1 - He can play OF as well as 1b

2 - He was a Top 5 MILB exit velo guy acc. to BA and Royals internally might see that number. — Clint Scoles (@ClintScoles) July 31, 2018

With this, O’Hearn defied all logic when it comes to league-to-league transitions. He was somehow better. He never missed a beat, hitting a home run in his first major league game, hitting for a 138 wRC+ in the month of August, and a 157 wRC+ for September. It seems that most of this was all driven by his elite mark in exit velocity. Among 390 hitters with at least 100 results, O’Hearn posted the 31st best mark in exit velocity. Amazingly enough, O’Hearn’s ISO was the fifth best mark in the history of baseball (1871-) by a rookie hitter.

Top 10 rookie ISO’s in the history of baseball # Name Team PA ISO # Name Team PA ISO 1 Rhys Hoskins Phillies 212 0.359 2 Matt Olson Athletics 244 0.357 3 Gary Sanchez Yankees 231 0.355 4 Rudy York Tigers 424 0.339 5 Ryan O'Hearn Royals 170 0.336 6 Aaron Judge Yankees 773 0.319 7 Mark McGwire Athletics 699 0.316 8 Khris Davis Brewers 153 0.316 9 Adam Dunn Reds 286 0.316 10 Ryan Schimpf Padres 330 0.315

Even in a relatively short sample size, O’Hearn’s debut performance was not just one of the more surprising developments in 2018, but in recent history. Exporting data on all Triple-A hitters and major league rookies since 2006, I matched up every rookie season with their same season performance in Triple-A. On average, hitters see about a 36 percent drop in wRC+ moving up from Triple-A. As a whole, their ISO drops from .178 to .140. All as expected.

Among these 238 instances that I found that qualified for this research, O’Hearn had the largest jump in wRC+ from Triple-A to the major leagues and it wasn’t even close (+66 points, next closest was 2007 James Loney at +52, third highest was 2018 Luke Voit at +51). The same went for ISO, as his change (+.177) was also the largest differential of those 238. Right behind him were two recent Yankees rookie hitters, Voit and Gary Sanchez.

After looking at this data, I wondered if and how long this surprising success was sustained. Looking at some of the more comparable Triple-A to MLB changes to that of O’Hearn’s, I found the average wRC+ for their last season in Triple-A, their first Major League stint, and their second full Major League season. The results weren’t great, as the median drop in wRC+ between the first and second Major League season was -39. Essentially, most of these hitters were returning to their Triple-A selves.

Comparable debuts to Ryan O’Hearn and the following season Seasons Name AAA wRC+ 1st Year wRC+ 2nd Year wRC+ Change Seasons Name AAA wRC+ 1st Year wRC+ 2nd Year wRC+ Change 2007/2008 James Loney 85 137 102 -35 2012/2013 Scooter Gennett 84 129 104 -25 2013/2014 Khris Davis 115 158 107 -51 2016/2017 Gary Sanchez 131 170 129 -41 2006/2007 Ryan Theriot 101 140 73 -67 2006/2007 Chris Duncan 113 143 117 -26 2011/2012 Brian Bogusevic 93 122 66 -56 2017/2018 Matt Olson 137 163 117 -46 2007/2008 Brendan Ryan 74 100 63 -37 2015/2016 Travis Shaw 96 118 88 -30 -- AVERAGE 103 138 97 -39

If we go off the lose basis of -39 change in wRC+, that would put O’Hearn in the ballpark of 110-115 for 2019. This would turn him into more of a league-average player than a hitter pacing for 40+ home runs. Expecting 2018 Matt Olson results would seem fair.

O’Hearn’s rookie season defied logic to the point of where his fantastic debut almost seemed too good to be true. History suggests regression is coming, but this isn’t all bad. Even with his struggles in Triple-A, there’s still a plenty long enough track record of him putting up good seasonal hitting performances, he still holds significantly above-average raw power and great quality of contact skills, and he’s running into 2019 with a confidence stemmed from his debut.

As interesting as 2018 was for Ryan O’Hearn, his follow up could be even more riveting.

Patrick Brennan loves to research pitchers and minor leaguers with data. You can find additional work of his at Royals Review and Royals Farm Report. You can also find him on Twitter @paintingcorner.