I double checked this after reading a 538 article that had Ohtani rated higher, had him headed for 9 and the next best guy headed for 7 and claimed the 2 WAR difference was historical. However that is more that no one else having a 9 WAR season this year, and many years there is.
A fair number of hitters and pitchers have put up 10 WAR seasons in the last 30 years. Pedro Martinez, Clemens, Johnson, A-Rod, Bonds, Trout, Ripken, Henderson, Mookie Betts
Truly historic value would be more like 11, 12 WAR. Which Ohtani could do if he pitched more innings and improved his on base percentage.