I debuted Cleaning the Glass Insider last year with three articles that detailed the big-picture questions I had about the coming season. As I wrote:

Today, the third and final question I asked: Will the plus-minus machines keep humming on new teams?

When I asked this question before last season, I started off by introducing the pros and cons of relying on plus-minus in its various forms for player evaluation, concluding by writing:

>One helpful rule of thumb: the more data, across more teams and in more roles, the more confidence we have that these metrics are picking up on something real and repeatable…But a front office, of course, can’t wait until a player’s career is done to judge whether these metrics were picking up on something real.

That led right into what I wanted to watch in the 2017-18 season:

>Four players changed teams this summer that have looked much better by plus-minus metrics than their conventional reputations would suggest: Ricky Rubio, Jae Crowder, Amir Johnson, and Patrick Patterson. For each of them there are reasons to think the plus-minus is picking up on something real, and for each there are reasons to be skeptical.

That all four players changed teams in the same offseason provided a nice test. Decision-makers who might be swayed to acquire a player because of his strongly positive plus-minus (or high rating in one of its adjusted flavors, like ESPN’s Real Plus-Minus) could watch these cases and see how much they could count on that performance continuing. All of them had a good-sized track record, across multiple teams and roles, to suggest that their plus-minus was picking up on something real. Now we could see how robust it was.