Great baseball analogy, a sport in which analytics has become an increasingly large component of the game....analystics would argue that this will eventually regress to the mean. Our batting average was well above our expected batting average last decade and this decade that is reversing, hence the regression. Now, I understand the valid arguments that this is more than simple regression and while that may be true, it is gong to take some time to know for certain.
Each of those 4 season were -WPO, except for 2017-2018, which was carried by the huge March and epic NAO blocking....again, no argument from me that the +WPO attributabed PAC jet is a problem right now.