this is not a Purdue problem as it occurs with other teams, defenses change from year to year where they put more emphasis on certain players.
Jordan for Iowa shot 43% from 3 as a SO then he shot 38.3% from 3 as a JR, the main reason was he became the focal point of the defense.
to single out just the Purdue players is shall we say simple minded just to be polite.
I’m saying that having a player or two shoot worse from year to year shouldn’t be surprising. It is more common for that to happen than it is for everyone to shoot the same or better.
It’s the Purdue poster saying Purdue players all shoot the same or better every year.