We had 45 last year (38+7), and Pickett made 46. Not sure of the mechanism that allowed Pickett onto the rookie list when Grigg retired. Maybe Grigg was excluded and one of the rookies was temporarily elevated to replace Grigg and keep the minimum 38 on the main list?
I read an article at the time that Grigg's retirement actually made no difference in adding Pickett but it seems no one really wanted to ruin the romance so the mis-truth became the truth.