Why Ryan O'Hearn's Projections Are Wrong

I don't think any knowledgeable baseball fan looks at Ryan O'Hearn's 2018 season and thinks he can replicate that performance over 600 plate appearances (He's going to hit 40 HRs baby). Still the projections on him that I have seen looked too low, so I started doing some math to see what his season would need to look like to match those projections.

Last year O'Hearn slashed .262/.353/.597 for a wRC+ of 153. The big caveat to that is that against right handed pitching he was Barry Bonds (.313/.403/.705 and 194), but against left handed pitching he was only slightly better than most pitchers trying to hit (.108/.195/.270 and 24). The Royals protected him a little from left handers having him face them in 24% of plate appearances. The first thing I did was created a weighted slash line based on facing a league average number of lefties.

In 2018 and 2017, for all major league plate appearances (all stats from Fangraphs), 28.4% and 28% were against left handed pitching respectively. So O'Hearn's 24% wasn't too far out of line. If he had the same slash line in his splits but you move 4% from right to left he would have hit .256/.346/.583, which is still good. Last year the closest comp to this line was Trevor Story at .291/.348/.567 and a wRC+ of 127. I would take that.

Next I took that weighted slash line and adjusted it down to see what the projections would be expecting. If you hold his atrocious line against lefties constant, his right handed slash line would need to drop to roughly .280/.350/.480 to look similar the projections on Fangraphs, Steamer and THE BAT. That is a drop in his split versus righties of 33 batting average points, 53 points of on base, and 225 of slug!!!! I expect a regression, but over 200 slugging points seems like a crazy amount to expect. Especially since it is holding his bad left splits constant and I would expect he can improve those splits and require and even larger drop in this split to match the projections.

There is reason to believe this would need to be slightly less extreme. Good left handed hitters will tend to face left handed pitching slightly more often playing every day because of reliever usage. The opposing teams will likely force the best hitters into same handed situations. For instance, Mike Moustakas faced 30% left handed last season, but that is only 2% more than average, so not a large effect.

Regardless of what you think of Ryan O'Hearn, last season happened. For the projections to actually come true, last season would have to have been a complete mirage, and I mean pretty much all of his success would have to been from the fluke/dumb luck column. That seems unlikely in my opinion, so I am going to say right now the projections are just flat out wrong.