Here's the first 100 rows of the sheet. The rows that display are AL outfielders; the hidden row are NL outfielders.

So my understanding is that averageif takes three arguments: the first is the range of values [in this case, all the cells in column AB]; TRUE, which I understand references those cells that are seen, and then one last argument, which is another range of cells. Here's where I get lost: on this sheet, where does the final argument come from?

Column AC is supposed to be Z values, so I also need STDEVIF for column AB as well, so I can then calculate the standard deviation from the mean for each AL player.

Thanks!